21370957 has 4 divisors (see below), whose sum is σ = 21868000. Its totient is φ = 20873916.

The previous prime is 21370927. The next prime is 21370981. The reversal of 21370957 is 75907312.

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 a cyclic number.

It is not a de Polignac number, because 21370957 - 2⁷ = 21370829 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21370927) 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, 248457 + ... + 248542.

It is an arithmetic number, because the mean of its divisors is an integer number (5467000).

Almost surely, 2^21370957 is an apocalyptic number.

It is an amenable number.

21370957 is a deficient number, since it is larger than the sum of its proper divisors (497043).

21370957 is an equidigital number, since it uses as much as digits as its factorization.

21370957 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 497042.

The product of its (nonzero) digits is 13230, while the sum is 34.

The square root of 21370957 is about 4622.8732407454. The cubic root of 21370957 is about 277.5074564455.

The spelling of 21370957 in words is "twenty-one million, three hundred seventy thousand, nine hundred fifty-seven".