21261800 has 48 divisors (see below), whose sum is σ = 56499360. Its totient is φ = 7289280.

The previous prime is 21261797. The next prime is 21261803. The reversal of 21261800 is 816212.

It is an interprime number because it is at equal distance from previous prime (21261797) and next prime (21261803).

It is a Harshad number since it is a multiple of its sum of digits (20).

It is not an unprimeable number, because it can be changed into a prime (21261803) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6194 + ... + 8993.

It is an arithmetic number, because the mean of its divisors is an integer number (1177070).

Almost surely, 2^21261800 is an apocalyptic number.

21261800 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21261800 is an abundant number, since it is smaller than the sum of its proper divisors (35237560).

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

21261800 is a wasteful number, since it uses less digits than its factorization.

21261800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15210 (or 15201 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 20.

The square root of 21261800 is about 4611.0519407181. The cubic root of 21261800 is about 277.0341723449.

The spelling of 21261800 in words is "twenty-one million, two hundred sixty-one thousand, eight hundred".