21710537 has 2 divisors, whose sum is σ = 21710538. Its totient is φ = 21710536.

The previous prime is 21710519. The next prime is 21710567. The reversal of 21710537 is 73501712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18412681 + 3297856 = 4291^2 + 1816^2 .

It is a cyclic number.

It is not a de Polignac number, because 21710537 - 2⁸ = 21710281 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21710567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10855268 + 10855269.

It is an arithmetic number, because the mean of its divisors is an integer number (10855269).

Almost surely, 2^21710537 is an apocalyptic number.

It is an amenable number.

21710537 is a deficient number, since it is larger than the sum of its proper divisors (1).

21710537 is an equidigital number, since it uses as much as digits as its factorization.

21710537 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1470, while the sum is 26.

The square root of 21710537 is about 4659.4567279888. The cubic root of 21710537 is about 278.9695842624.

The spelling of 21710537 in words is "twenty-one million, seven hundred ten thousand, five hundred thirty-seven".