21562500 has 96 divisors (see below), whose sum is σ = 65624832. Its totient is φ = 5500000.

The previous prime is 21562493. The next prime is 21562501. The reversal of 21562500 is 526512.

It is not an unprimeable number, because it can be changed into a prime (21562501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 937489 + ... + 937511.

It is an arithmetic number, because the mean of its divisors is an integer number (683592).

Almost surely, 2^21562500 is an apocalyptic number.

21562500 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 21562500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32812416).

21562500 is an abundant number, since it is smaller than the sum of its proper divisors (44062332).

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

21562500 is an frugal number, since it uses more digits than its factorization.

21562500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65 (or 33 counting only the distinct ones).

The product of its (nonzero) digits is 600, while the sum is 21.

The square root of 21562500 is about 4643.5439052517. The cubic root of 21562500 is about 278.3340703802.

It can be divided in two parts, 2156 and 2500, that added together give a triangular number (4656 = T₉₆).

The spelling of 21562500 in words is "twenty-one million, five hundred sixty-two thousand, five hundred".