21357709115 has 4 divisors (see below), whose sum is σ = 25629250944. Its totient is φ = 17086167288.

The previous prime is 21357709091. The next prime is 21357709123. The reversal of 21357709115 is 51190775312.

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-21357709115 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2135770907 + ... + 2135770916.

It is an arithmetic number, because the mean of its divisors is an integer number (6407312736).

Almost surely, 2^21357709115 is an apocalyptic number.

21357709115 is a deficient number, since it is larger than the sum of its proper divisors (4271541829).

21357709115 is an equidigital number, since it uses as much as digits as its factorization.

21357709115 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4271541828.

The product of its (nonzero) digits is 66150, while the sum is 41.

The spelling of 21357709115 in words is "twenty-one billion, three hundred fifty-seven million, seven hundred nine thousand, one hundred fifteen".