21105456 has 20 divisors (see below), whose sum is σ = 54522552. Its totient is φ = 7035136.

The previous prime is 21105443. The next prime is 21105457. The reversal of 21105456 is 65450112.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is not an unprimeable number, because it can be changed into a prime (21105457) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 219801 + ... + 219896.

Almost surely, 2^21105456 is an apocalyptic number.

It is an amenable number.

21105456 is an abundant number, since it is smaller than the sum of its proper divisors (33417096).

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

21105456 is a wasteful number, since it uses less digits than its factorization.

21105456 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 439708 (or 439702 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 24.

The square root of 21105456 is about 4594.0674788253. The cubic root of 21105456 is about 276.3534643805.

Adding to 21105456 its reverse (65450112), we get a palindrome (86555568).

The spelling of 21105456 in words is "twenty-one million, one hundred five thousand, four hundred fifty-six".