641720879 has 4 divisors (see below), whose sum is σ = 679469184. Its totient is φ = 603972576.

The previous prime is 641720869. The next prime is 641720887. The reversal of 641720879 is 978027146.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-641720879 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 (641720819) 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, 18874127 + ... + 18874160.

It is an arithmetic number, because the mean of its divisors is an integer number (169867296).

Almost surely, 2^641720879 is an apocalyptic number.

641720879 is a deficient number, since it is larger than the sum of its proper divisors (37748305).

641720879 is a wasteful number, since it uses less digits than its factorization.

641720879 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37748304.

The product of its (nonzero) digits is 169344, while the sum is 44.

The square root of 641720879 is about 25332.2103062484. The cubic root of 641720879 is about 862.5455850443.

The spelling of 641720879 in words is "six hundred forty-one million, seven hundred twenty thousand, eight hundred seventy-nine".