65631221647 has 4 divisors (see below), whose sum is σ = 65631822480. Its totient is φ = 65630620816.

The previous prime is 65631221639. The next prime is 65631221651. The reversal of 65631221647 is 74612213656.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 65631221647 - 2³ = 65631221639 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (65631221627) 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, 85147 + ... + 372172.

It is an arithmetic number, because the mean of its divisors is an integer number (16407955620).

Almost surely, 2^65631221647 is an apocalyptic number.

65631221647 is a deficient number, since it is larger than the sum of its proper divisors (600833).

65631221647 is a wasteful number, since it uses less digits than its factorization.

65631221647 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 600832.

The product of its digits is 362880, while the sum is 43.

The spelling of 65631221647 in words is "sixty-five billion, six hundred thirty-one million, two hundred twenty-one thousand, six hundred forty-seven".