21505968 has 60 divisors (see below), whose sum is σ = 65663208. Its totient is φ = 6516480.

The previous prime is 21505949. The next prime is 21505999. The reversal of 21505968 is 86950512.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5205 + ... + 8372.

Almost surely, 2^21505968 is an apocalyptic number.

It is an amenable number.

21505968 is an abundant number, since it is smaller than the sum of its proper divisors (44157240).

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

21505968 is a wasteful number, since it uses less digits than its factorization.

21505968 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13602 (or 13593 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 36.

The square root of 21505968 is about 4637.4527490854. The cubic root of 21505968 is about 278.0906144924.

It can be divided in two parts, 2150 and 5968, that added together give a palindrome (8118).

The spelling of 21505968 in words is "twenty-one million, five hundred five thousand, nine hundred sixty-eight".