21171711651 has 32 divisors (see below), whose sum is σ = 31446128448. Its totient is φ = 12609884160.

The previous prime is 21171711643. The next prime is 21171711677. The reversal of 21171711651 is 15611717112.

It is not a de Polignac number, because 21171711651 - 2³ = 21171711643 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21171711751) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 59460 + ... + 214193.

It is an arithmetic number, because the mean of its divisors is an integer number (982691514).

Almost surely, 2^21171711651 is an apocalyptic number.

21171711651 is a deficient number, since it is larger than the sum of its proper divisors (10274416797).

21171711651 is a wasteful number, since it uses less digits than its factorization.

21171711651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 273751.

The product of its digits is 2940, while the sum is 33.

The spelling of 21171711651 in words is "twenty-one billion, one hundred seventy-one million, seven hundred eleven thousand, six hundred fifty-one".