21513893 has 2 divisors, whose sum is σ = 21513894. Its totient is φ = 21513892.

The previous prime is 21513887. The next prime is 21513929. The reversal of 21513893 is 39831512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21224449 + 289444 = 4607^2 + 538^2 .

It is a cyclic number.

It is not a de Polignac number, because 21513893 - 2⁸ = 21513637 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21513593) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10756946 + 10756947.

It is an arithmetic number, because the mean of its divisors is an integer number (10756947).

Almost surely, 2^21513893 is an apocalyptic number.

It is an amenable number.

21513893 is a deficient number, since it is larger than the sum of its proper divisors (1).

21513893 is an equidigital number, since it uses as much as digits as its factorization.

21513893 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6480, while the sum is 32.

The square root of 21513893 is about 4638.3071265280. The cubic root of 21513893 is about 278.1247693134.

The spelling of 21513893 in words is "twenty-one million, five hundred thirteen thousand, eight hundred ninety-three".