21531879651 has 8 divisors (see below), whose sum is σ = 28915714240. Its totient is φ = 14251315752.

The previous prime is 21531879619. The next prime is 21531879683. The reversal of 21531879651 is 15697813512.

It is an interprime number because it is at equal distance from previous prime (21531879619) and next prime (21531879683).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21531879651 - 2⁵ = 21531879619 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 21531879651.

It is not an unprimeable number, because it can be changed into a prime (21531879451) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25817185 + ... + 25818018.

It is an arithmetic number, because the mean of its divisors is an integer number (3614464280).

Almost surely, 2^21531879651 is an apocalyptic number.

21531879651 is a deficient number, since it is larger than the sum of its proper divisors (7383834589).

21531879651 is a wasteful number, since it uses less digits than its factorization.

21531879651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51635345.

The product of its digits is 453600, while the sum is 48.

The spelling of 21531879651 in words is "twenty-one billion, five hundred thirty-one million, eight hundred seventy-nine thousand, six hundred fifty-one".