21865707 has 10 divisors (see below), whose sum is σ = 32663708. Its totient is φ = 14577084.

The previous prime is 21865687. The next prime is 21865721. The reversal of 21865707 is 70756812.

21865707 is a `hidden beast` number, since 2 + 1 + 86 + 570 + 7 = 666.

It is not a de Polignac number, because 21865707 - 2⁷ = 21865579 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21865777) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 134893 + ... + 135054.

Almost surely, 2^21865707 is an apocalyptic number.

21865707 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

21865707 is a deficient number, since it is larger than the sum of its proper divisors (10798001).

21865707 is an equidigital number, since it uses as much as digits as its factorization.

21865707 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 269959 (or 269950 counting only the distinct ones).

The product of its (nonzero) digits is 23520, while the sum is 36.

The square root of 21865707 is about 4676.0781644451. The cubic root of 21865707 is about 279.6326261915.

The spelling of 21865707 in words is "twenty-one million, eight hundred sixty-five thousand, seven hundred seven".