21907871 has 2 divisors, whose sum is σ = 21907872. Its totient is φ = 21907870.

The previous prime is 21907867. The next prime is 21907877. The reversal of 21907871 is 17870912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21907871 - 2² = 21907867 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is equal to p_1383767 and since 21907871 and 1383767 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21907877) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10953935 + 10953936.

It is an arithmetic number, because the mean of its divisors is an integer number (10953936).

Almost surely, 2^21907871 is an apocalyptic number.

21907871 is a deficient number, since it is larger than the sum of its proper divisors (1).

21907871 is an equidigital number, since it uses as much as digits as its factorization.

21907871 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7056, while the sum is 35.

The square root of 21907871 is about 4680.5844720505. The cubic root of 21907871 is about 279.8122508369.

The spelling of 21907871 in words is "twenty-one million, nine hundred seven thousand, eight hundred seventy-one".