71644663821 has 16 divisors (see below), whose sum is σ = 99411984000. Its totient is φ = 45839951808.

The previous prime is 71644663799. The next prime is 71644663873. The reversal of 71644663821 is 12836644617.

It is not a de Polignac number, because 71644663821 - 2⁵ = 71644663789 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71644665821) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2451046 + ... + 2480103.

It is an arithmetic number, because the mean of its divisors is an integer number (6213249000).

Almost surely, 2^71644663821 is an apocalyptic number.

It is an amenable number.

71644663821 is a deficient number, since it is larger than the sum of its proper divisors (27767320179).

71644663821 is a wasteful number, since it uses less digits than its factorization.

71644663821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4931348.

The product of its digits is 1161216, while the sum is 48.

The spelling of 71644663821 in words is "seventy-one billion, six hundred forty-four million, six hundred sixty-three thousand, eight hundred twenty-one".