21712057 has 2 divisors, whose sum is σ = 21712058. Its totient is φ = 21712056.

The previous prime is 21711973. The next prime is 21712063. The reversal of 21712057 is 75021712.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21706281 + 5776 = 4659^2 + 76^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21712057 is a prime.

It is not a weakly prime, because it can be changed into another prime (21712357) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10856028 + 10856029.

It is an arithmetic number, because the mean of its divisors is an integer number (10856029).

Almost surely, 2^21712057 is an apocalyptic number.

It is an amenable number.

21712057 is a deficient number, since it is larger than the sum of its proper divisors (1).

21712057 is an equidigital number, since it uses as much as digits as its factorization.

21712057 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 980, while the sum is 25.

The square root of 21712057 is about 4659.6198342783. The cubic root of 21712057 is about 278.9760945247.

Adding to 21712057 its reverse (75021712), we get a palindrome (96733769).

The spelling of 21712057 in words is "twenty-one million, seven hundred twelve thousand, fifty-seven".