21254805 has 80 divisors (see below), whose sum is σ = 44884224. Its totient is φ = 9486720.

The previous prime is 21254797. The next prime is 21254813. The reversal of 21254805 is 50845212.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21254797) and next prime (21254813).

It is not a de Polignac number, because 21254805 - 2³ = 21254797 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 57732 + ... + 58098.

Almost surely, 2^21254805 is an apocalyptic number.

It is an amenable number.

21254805 is an abundant number, since it is smaller than the sum of its proper divisors (23629419).

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

21254805 is a wasteful number, since it uses less digits than its factorization.

21254805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 408 (or 399 counting only the distinct ones).

The product of its (nonzero) digits is 3200, while the sum is 27.

The square root of 21254805 is about 4610.2933746129. The cubic root of 21254805 is about 277.0037881726.

The spelling of 21254805 in words is "twenty-one million, two hundred fifty-four thousand, eight hundred five".