21979297 has 2 divisors, whose sum is σ = 21979298. Its totient is φ = 21979296.

The previous prime is 21979289. The next prime is 21979319. The reversal of 21979297 is 79297912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13476241 + 8503056 = 3671^2 + 2916^2 .

It is a cyclic number.

It is not a de Polignac number, because 21979297 - 2³ = 21979289 is a prime.

It is a super-2 number, since 2×21979297² = 966178993228418, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21979247) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10989648 + 10989649.

It is an arithmetic number, because the mean of its divisors is an integer number (10989649).

Almost surely, 2^21979297 is an apocalyptic number.

It is an amenable number.

21979297 is a deficient number, since it is larger than the sum of its proper divisors (1).

21979297 is an equidigital number, since it uses as much as digits as its factorization.

21979297 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 142884, while the sum is 46.

The square root of 21979297 is about 4688.2082931542. The cubic root of 21979297 is about 280.1160106009.

The spelling of 21979297 in words is "twenty-one million, nine hundred seventy-nine thousand, two hundred ninety-seven".