21207708 has 36 divisors (see below), whose sum is σ = 54294240. Its totient is φ = 6978816.

The previous prime is 21207707. The next prime is 21207709. The reversal of 21207708 is 80770212.

It is an interprime number because it is at equal distance from previous prime (21207707) and next prime (21207709).

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×21207708² = 899533757226528, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21207707) 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, 885 + ... + 6572.

Almost surely, 2^21207708 is an apocalyptic number.

It is an amenable number.

21207708 is an abundant number, since it is smaller than the sum of its proper divisors (33086532).

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

21207708 is a wasteful number, since it uses less digits than its factorization.

21207708 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7546 (or 7541 counting only the distinct ones).

The product of its (nonzero) digits is 1568, while the sum is 27.

The square root of 21207708 is about 4605.1827325308. The cubic root of 21207708 is about 276.7990392507.

The spelling of 21207708 in words is "twenty-one million, two hundred seven thousand, seven hundred eight".