21307279397 has 2 divisors, whose sum is σ = 21307279398. Its totient is φ = 21307279396.

The previous prime is 21307279387. The next prime is 21307279439. The reversal of 21307279397 is 79397270312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20200652641 + 1106626756 = 142129^2 + 33266^2 .

It is a cyclic number.

It is not a de Polignac number, because 21307279397 - 2¹⁴ = 21307263013 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21307279387) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10653639698 + 10653639699.

It is an arithmetic number, because the mean of its divisors is an integer number (10653639699).

Almost surely, 2^21307279397 is an apocalyptic number.

It is an amenable number.

21307279397 is a deficient number, since it is larger than the sum of its proper divisors (1).

21307279397 is an equidigital number, since it uses as much as digits as its factorization.

21307279397 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1000188, while the sum is 50.

The spelling of 21307279397 in words is "twenty-one billion, three hundred seven million, two hundred seventy-nine thousand, three hundred ninety-seven".