21304440397 has 2 divisors, whose sum is σ = 21304440398. Its totient is φ = 21304440396.

The previous prime is 21304440389. The next prime is 21304440473. The reversal of 21304440397 is 79304440312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15202643401 + 6101796996 = 123299^2 + 78114^2 .

It is a cyclic number.

It is not a de Polignac number, because 21304440397 - 2³ = 21304440389 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21304443397) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10652220198 + 10652220199.

It is an arithmetic number, because the mean of its divisors is an integer number (10652220199).

Almost surely, 2^21304440397 is an apocalyptic number.

It is an amenable number.

21304440397 is a deficient number, since it is larger than the sum of its proper divisors (1).

21304440397 is an equidigital number, since it uses as much as digits as its factorization.

21304440397 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72576, while the sum is 37.

The spelling of 21304440397 in words is "twenty-one billion, three hundred four million, four hundred forty thousand, three hundred ninety-seven".