21371907397 has 4 divisors (see below), whose sum is σ = 21372828480. Its totient is φ = 21370986316.

The previous prime is 21371907383. The next prime is 21371907407. The reversal of 21371907397 is 79370917312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21371907397 - 2¹¹ = 21371905349 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21371907397.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21371907097) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 424813 + ... + 472450.

It is an arithmetic number, because the mean of its divisors is an integer number (5343207120).

Almost surely, 2^21371907397 is an apocalyptic number.

It is an amenable number.

21371907397 is a deficient number, since it is larger than the sum of its proper divisors (921083).

21371907397 is an equidigital number, since it uses as much as digits as its factorization.

21371907397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 921082.

The product of its (nonzero) digits is 500094, while the sum is 49.

The spelling of 21371907397 in words is "twenty-one billion, three hundred seventy-one million, nine hundred seven thousand, three hundred ninety-seven".