21613457 has 2 divisors, whose sum is σ = 21613458. Its totient is φ = 21613456.

The previous prime is 21613451. The next prime is 21613483. The reversal of 21613457 is 75431612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21613201 + 256 = 4649^2 + 16^2 .

It is a cyclic number.

It is not a de Polignac number, because 21613457 - 2⁴ = 21613441 is a prime.

It is equal to p_1366328 and since 21613457 and 1366328 have the same sum of digits, it is a Honaker prime.

It is a plaindrome in base 11.

It is not a weakly prime, because it can be changed into another prime (21613451) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10806728 + 10806729.

It is an arithmetic number, because the mean of its divisors is an integer number (10806729).

Almost surely, 2^21613457 is an apocalyptic number.

It is an amenable number.

21613457 is a deficient number, since it is larger than the sum of its proper divisors (1).

21613457 is an equidigital number, since it uses as much as digits as its factorization.

21613457 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5040, while the sum is 29.

The square root of 21613457 is about 4649.0275327212. The cubic root of 21613457 is about 278.5531530668.

The spelling of 21613457 in words is "twenty-one million, six hundred thirteen thousand, four hundred fifty-seven".