65215631721 has 8 divisors (see below), whose sum is σ = 87314982304. Its totient is φ = 43296684480.

The previous prime is 65215631713. The next prime is 65215631743. The reversal of 65215631721 is 12713651256.

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

It is not a de Polignac number, because 65215631721 - 2³ = 65215631713 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 65215631721.

It is not an unprimeable number, because it can be changed into a prime (65215631821) 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, 45099991 + ... + 45101436.

It is an arithmetic number, because the mean of its divisors is an integer number (10914372788).

Almost surely, 2^65215631721 is an apocalyptic number.

It is an amenable number.

65215631721 is a deficient number, since it is larger than the sum of its proper divisors (22099350583).

65215631721 is a wasteful number, since it uses less digits than its factorization.

65215631721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90201671.

The product of its digits is 75600, while the sum is 39.

The spelling of 65215631721 in words is "sixty-five billion, two hundred fifteen million, six hundred thirty-one thousand, seven hundred twenty-one".