21093913 has 2 divisors, whose sum is σ = 21093914. Its totient is φ = 21093912.

The previous prime is 21093907. The next prime is 21093997. The reversal of 21093913 is 31939012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20178064 + 915849 = 4492^2 + 957^2 .

It is a cyclic number.

It is not a de Polignac number, because 21093913 - 2¹³ = 21085721 is a prime.

It is not a weakly prime, because it can be changed into another prime (21093013) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10546956 + 10546957.

It is an arithmetic number, because the mean of its divisors is an integer number (10546957).

Almost surely, 2^21093913 is an apocalyptic number.

It is an amenable number.

21093913 is a deficient number, since it is larger than the sum of its proper divisors (1).

21093913 is an equidigital number, since it uses as much as digits as its factorization.

21093913 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1458, while the sum is 28.

The square root of 21093913 is about 4592.8110128765. The cubic root of 21093913 is about 276.3030740965.

The spelling of 21093913 in words is "twenty-one million, ninety-three thousand, nine hundred thirteen".