21879701 has 2 divisors, whose sum is σ = 21879702. Its totient is φ = 21879700.

The previous prime is 21879661. The next prime is 21879703. The reversal of 21879701 is 10797812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21022225 + 857476 = 4585^2 + 926^2 .

It is a cyclic number.

It is not a de Polignac number, because 21879701 - 2²² = 17685397 is a prime.

It is a super-4 number, since 4×21879701⁴ (a number of 30 digits) contains 4444 as substring.

It is a Sophie Germain prime.

Together with 21879703, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21879703) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10939850 + 10939851.

It is an arithmetic number, because the mean of its divisors is an integer number (10939851).

Almost surely, 2^21879701 is an apocalyptic number.

It is an amenable number.

21879701 is a deficient number, since it is larger than the sum of its proper divisors (1).

21879701 is an equidigital number, since it uses as much as digits as its factorization.

21879701 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7056, while the sum is 35.

The square root of 21879701 is about 4677.5742645093. The cubic root of 21879701 is about 279.6922682062.

The spelling of 21879701 in words is "twenty-one million, eight hundred seventy-nine thousand, seven hundred one".