21261807 has 12 divisors (see below), whose sum is σ = 35098960. Its totient is φ = 12149568.

The previous prime is 21261803. The next prime is 21261809. The reversal of 21261807 is 70816212.

It is not a de Polignac number, because 21261807 - 2² = 21261803 is a prime.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21261803) 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, 168682 + ... + 168807.

Almost surely, 2^21261807 is an apocalyptic number.

21261807 is a deficient number, since it is larger than the sum of its proper divisors (13837153).

21261807 is a wasteful number, since it uses less digits than its factorization.

21261807 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 337502 (or 337499 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 27.

The square root of 21261807 is about 4611.0526997639. The cubic root of 21261807 is about 277.0342027475.

The spelling of 21261807 in words is "twenty-one million, two hundred sixty-one thousand, eight hundred seven".