21579401 has 2 divisors, whose sum is σ = 21579402. Its totient is φ = 21579400.

The previous prime is 21579377. The next prime is 21579431. The reversal of 21579401 is 10497512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21381376 + 198025 = 4624^2 + 445^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21579401 is a prime.

It is a Chen prime.

It is equal to p_1364276 and since 21579401 and 1364276 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (21579431) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10789700 + 10789701.

It is an arithmetic number, because the mean of its divisors is an integer number (10789701).

Almost surely, 2^21579401 is an apocalyptic number.

It is an amenable number.

21579401 is a deficient number, since it is larger than the sum of its proper divisors (1).

21579401 is an equidigital number, since it uses as much as digits as its factorization.

21579401 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2520, while the sum is 29.

The square root of 21579401 is about 4645.3633872928. The cubic root of 21579401 is about 278.4067721480.

The spelling of 21579401 in words is "twenty-one million, five hundred seventy-nine thousand, four hundred one".