21086507 has 4 divisors (see below), whose sum is σ = 22708560. Its totient is φ = 19464456.

The previous prime is 21086501. The next prime is 21086543. The reversal of 21086507 is 70568012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21086507 - 2⁴ = 21086491 is a prime.

It is a super-2 number, since 2×21086507² = 889281554922098, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21086507.

It is not an unprimeable number, because it can be changed into a prime (21086501) 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, 811007 + ... + 811032.

It is an arithmetic number, because the mean of its divisors is an integer number (5677140).

Almost surely, 2^21086507 is an apocalyptic number.

21086507 is a deficient number, since it is larger than the sum of its proper divisors (1622053).

21086507 is a wasteful number, since it uses less digits than its factorization.

21086507 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1622052.

The product of its (nonzero) digits is 3360, while the sum is 29.

The square root of 21086507 is about 4592.0046820534. The cubic root of 21086507 is about 276.2707339597.

The spelling of 21086507 in words is "twenty-one million, eighty-six thousand, five hundred seven".