21393739 has 2 divisors, whose sum is σ = 21393740. Its totient is φ = 21393738.

The previous prime is 21393727. The next prime is 21393761. The reversal of 21393739 is 93739312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21393739 - 2⁵ = 21393707 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21393698 and 21393707.

It is not a weakly prime, because it can be changed into another prime (21393709) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10696869 + 10696870.

It is an arithmetic number, because the mean of its divisors is an integer number (10696870).

Almost surely, 2^21393739 is an apocalyptic number.

21393739 is a deficient number, since it is larger than the sum of its proper divisors (1).

21393739 is an equidigital number, since it uses as much as digits as its factorization.

21393739 is an evil number, because the sum of its binary digits is even.

The product of its digits is 30618, while the sum is 37.

The square root of 21393739 is about 4625.3366363974. The cubic root of 21393739 is about 277.6060314986.

The spelling of 21393739 in words is "twenty-one million, three hundred ninety-three thousand, seven hundred thirty-nine".