21610957 has 2 divisors, whose sum is σ = 21610958. Its totient is φ = 21610956.

The previous prime is 21610949. The next prime is 21610991. The reversal of 21610957 is 75901612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18957316 + 2653641 = 4354^2 + 1629^2 .

It is a cyclic number.

It is not a de Polignac number, because 21610957 - 2³ = 21610949 is a prime.

It is a zygodrome in base 3.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21610907) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10805478 + 10805479.

It is an arithmetic number, because the mean of its divisors is an integer number (10805479).

Almost surely, 2^21610957 is an apocalyptic number.

It is an amenable number.

21610957 is a deficient number, since it is larger than the sum of its proper divisors (1).

21610957 is an equidigital number, since it uses as much as digits as its factorization.

21610957 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3780, while the sum is 31.

The square root of 21610957 is about 4648.7586515112. The cubic root of 21610957 is about 278.5424126943.

The spelling of 21610957 in words is "twenty-one million, six hundred ten thousand, nine hundred fifty-seven".