21125000 has 84 divisors (see below), whose sum is σ = 53612595. Its totient is φ = 7800000.

The previous prime is 21124993. The next prime is 21125003. The reversal of 21125000 is 52112.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in 11 ways, for example, as 21104836 + 20164 = 4594^2 + 142^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=3250.

It is a hoax number, since the sum of its digits (11) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21125003) by changing a digit.

It is a polite number, since it can be written in 20 ways as a sum of consecutive naturals, for example, 1624994 + ... + 1625006.

Almost surely, 2^21125000 is an apocalyptic number.

21125000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21125000

21125000 is an abundant number, since it is smaller than the sum of its proper divisors (32487595).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21125000 is an frugal number, since it uses more digits than its factorization.

21125000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 62 (or 20 counting only the distinct ones).

The product of its (nonzero) digits is 20, while the sum is 11.

The square root of 21125000 is about 4596.1940777126. The cubic root of 21125000 is about 276.4387406839.

Adding to 21125000 its reverse (52112), we get a palindrome (21177112).

It can be divided in two parts, 2 and 1125000, that multiplied together give a square (2250000 = 1500²).

The spelling of 21125000 in words is "twenty-one million, one hundred twenty-five thousand".