21237413 has 2 divisors, whose sum is σ = 21237414. Its totient is φ = 21237412.

The previous prime is 21237409. The next prime is 21237427. The reversal of 21237413 is 31473212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15864289 + 5373124 = 3983^2 + 2318^2 .

It is a cyclic number.

It is not a de Polignac number, because 21237413 - 2² = 21237409 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21237493) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10618706 + 10618707.

It is an arithmetic number, because the mean of its divisors is an integer number (10618707).

Almost surely, 2^21237413 is an apocalyptic number.

It is an amenable number.

21237413 is a deficient number, since it is larger than the sum of its proper divisors (1).

21237413 is an equidigital number, since it uses as much as digits as its factorization.

21237413 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1008, while the sum is 23.

The square root of 21237413 is about 4608.4067745806. The cubic root of 21237413 is about 276.9282136610.

The spelling of 21237413 in words is "twenty-one million, two hundred thirty-seven thousand, four hundred thirteen".