21255402 has 32 divisors (see below), whose sum is σ = 48783744. Its totient is φ = 6048000.

The previous prime is 21255401. The next prime is 21255407. The reversal of 21255402 is 20455212.

It is a happy number.

It is a super-2 number, since 2×21255402² = 903584228363208, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is not an unprimeable number, because it can be changed into a prime (21255401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10902 + ... + 12702.

It is an arithmetic number, because the mean of its divisors is an integer number (1524492).

Almost surely, 2^21255402 is an apocalyptic number.

21255402 is an abundant number, since it is smaller than the sum of its proper divisors (27528342).

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

21255402 is a wasteful number, since it uses less digits than its factorization.

21255402 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2094.

The product of its (nonzero) digits is 800, while the sum is 21.

The square root of 21255402 is about 4610.3581205802. The cubic root of 21255402 is about 277.0063816208.

The spelling of 21255402 in words is "twenty-one million, two hundred fifty-five thousand, four hundred two".