21115000391 has 4 divisors (see below), whose sum is σ = 21115754400. Its totient is φ = 21114246384.

The previous prime is 21115000381. The next prime is 21115000411. The reversal of 21115000391 is 19300051112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21115000391 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21115000301) 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, 333311 + ... + 391568.

It is an arithmetic number, because the mean of its divisors is an integer number (5278938600).

Almost surely, 2^21115000391 is an apocalyptic number.

21115000391 is a deficient number, since it is larger than the sum of its proper divisors (754009).

21115000391 is an equidigital number, since it uses as much as digits as its factorization.

21115000391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 754008.

The product of its (nonzero) digits is 270, while the sum is 23.

The spelling of 21115000391 in words is "twenty-one billion, one hundred fifteen million, three hundred ninety-one", and thus it is an aban number.