21718471051 has 4 divisors (see below), whose sum is σ = 21751328704. Its totient is φ = 21685613400.

The previous prime is 21718471039. The next prime is 21718471079. The reversal of 21718471051 is 15017481712.

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

It is a cyclic number.

It is not a de Polignac number, because 21718471051 - 2¹³ = 21718462859 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 21718471051.

It is not an unprimeable number, because it can be changed into a prime (21718471351) 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, 16427835 + ... + 16429156.

It is an arithmetic number, because the mean of its divisors is an integer number (5437832176).

Almost surely, 2^21718471051 is an apocalyptic number.

21718471051 is a deficient number, since it is larger than the sum of its proper divisors (32857653).

21718471051 is an equidigital number, since it uses as much as digits as its factorization.

21718471051 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32857652.

The product of its (nonzero) digits is 15680, while the sum is 37.

The spelling of 21718471051 in words is "twenty-one billion, seven hundred eighteen million, four hundred seventy-one thousand, fifty-one".