21310439 has 2 divisors, whose sum is σ = 21310440. Its totient is φ = 21310438.

The previous prime is 21310433. The next prime is 21310451. The reversal of 21310439 is 93401312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21310439 - 2¹² = 21306343 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21310433) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10655219 + 10655220.

It is an arithmetic number, because the mean of its divisors is an integer number (10655220).

Almost surely, 2^21310439 is an apocalyptic number.

21310439 is a deficient number, since it is larger than the sum of its proper divisors (1).

21310439 is an equidigital number, since it uses as much as digits as its factorization.

21310439 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 648, while the sum is 23.

The square root of 21310439 is about 4616.3231039432. The cubic root of 21310439 is about 277.2452614524.

The spelling of 21310439 in words is "twenty-one million, three hundred ten thousand, four hundred thirty-nine".