21389713 has 2 divisors, whose sum is σ = 21389714. Its totient is φ = 21389712.

The previous prime is 21389699. The next prime is 21389729. The reversal of 21389713 is 31798312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13454224 + 7935489 = 3668^2 + 2817^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21389713 is a prime.

It is not a weakly prime, because it can be changed into another prime (21389743) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10694856 + 10694857.

It is an arithmetic number, because the mean of its divisors is an integer number (10694857).

Almost surely, 2^21389713 is an apocalyptic number.

It is an amenable number.

21389713 is a deficient number, since it is larger than the sum of its proper divisors (1).

21389713 is an equidigital number, since it uses as much as digits as its factorization.

21389713 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9072, while the sum is 34.

The square root of 21389713 is about 4624.9014043545. The cubic root of 21389713 is about 277.5886165593.

The spelling of 21389713 in words is "twenty-one million, three hundred eighty-nine thousand, seven hundred thirteen".