21992657 has 2 divisors, whose sum is σ = 21992658. Its totient is φ = 21992656.

The previous prime is 21992653. The next prime is 21992693. The reversal of 21992657 is 75629912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21613201 + 379456 = 4649^2 + 616^2 .

It is a cyclic number.

It is not a de Polignac number, because 21992657 - 2² = 21992653 is a prime.

It is not a weakly prime, because it can be changed into another prime (21992653) 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, 10996328 + 10996329.

It is an arithmetic number, because the mean of its divisors is an integer number (10996329).

Almost surely, 2^21992657 is an apocalyptic number.

It is an amenable number.

21992657 is a deficient number, since it is larger than the sum of its proper divisors (1).

21992657 is an equidigital number, since it uses as much as digits as its factorization.

21992657 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 68040, while the sum is 41.

The square root of 21992657 is about 4689.6329280659. The cubic root of 21992657 is about 280.1727547862.

The spelling of 21992657 in words is "twenty-one million, nine hundred ninety-two thousand, six hundred fifty-seven".