21580957 has 2 divisors, whose sum is σ = 21580958. Its totient is φ = 21580956.

The previous prime is 21580931. The next prime is 21580963. The reversal of 21580957 is 75908512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19236996 + 2343961 = 4386^2 + 1531^2 .

It is a cyclic number.

It is not a de Polignac number, because 21580957 - 2²³ = 13192349 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21580907) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10790478 + 10790479.

It is an arithmetic number, because the mean of its divisors is an integer number (10790479).

Almost surely, 2^21580957 is an apocalyptic number.

It is an amenable number.

21580957 is a deficient number, since it is larger than the sum of its proper divisors (1).

21580957 is an equidigital number, since it uses as much as digits as its factorization.

21580957 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 25200, while the sum is 37.

The square root of 21580957 is about 4645.5308630984. The cubic root of 21580957 is about 278.4134635683.

The spelling of 21580957 in words is "twenty-one million, five hundred eighty thousand, nine hundred fifty-seven".