21630957 has 4 divisors (see below), whose sum is σ = 28841280. Its totient is φ = 14420636.

The previous prime is 21630923. The next prime is 21630991. The reversal of 21630957 is 75903612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (21630923) and next prime (21630991).

It is a cyclic number.

It is not a de Polignac number, because 21630957 - 2¹⁹ = 21106669 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21630907) 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, 3605157 + ... + 3605162.

It is an arithmetic number, because the mean of its divisors is an integer number (7210320).

Almost surely, 2^21630957 is an apocalyptic number.

It is an amenable number.

21630957 is a deficient number, since it is larger than the sum of its proper divisors (7210323).

21630957 is an equidigital number, since it uses as much as digits as its factorization.

21630957 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7210322.

The product of its (nonzero) digits is 11340, while the sum is 33.

The square root of 21630957 is about 4650.9092659393. The cubic root of 21630957 is about 278.6283124937.

The spelling of 21630957 in words is "twenty-one million, six hundred thirty thousand, nine hundred fifty-seven".