21373361 has 2 divisors, whose sum is σ = 21373362. Its totient is φ = 21373360.

The previous prime is 21373351. The next prime is 21373379. The reversal of 21373361 is 16337312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20757136 + 616225 = 4556^2 + 785^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21373361 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21373361.

It is not a weakly prime, because it can be changed into another prime (21373351) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10686680 + 10686681.

It is an arithmetic number, because the mean of its divisors is an integer number (10686681).

Almost surely, 2^21373361 is an apocalyptic number.

It is an amenable number.

21373361 is a deficient number, since it is larger than the sum of its proper divisors (1).

21373361 is an equidigital number, since it uses as much as digits as its factorization.

21373361 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2268, while the sum is 26.

The square root of 21373361 is about 4623.1332448892. The cubic root of 21373361 is about 277.5178615779.

The spelling of 21373361 in words is "twenty-one million, three hundred seventy-three thousand, three hundred sixty-one".