643679919 has 8 divisors (see below), whose sum is σ = 953599920. Its totient is φ = 429119928.

The previous prime is 643679917. The next prime is 643679923. The reversal of 643679919 is 919976346.

It is not a de Polignac number, because 643679919 - 2¹ = 643679917 is a prime.

It is a super-2 number, since 2×643679919² = 828647676247693122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643679917) 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, 11919972 + ... + 11920025.

It is an arithmetic number, because the mean of its divisors is an integer number (119199990).

Almost surely, 2^643679919 is an apocalyptic number.

643679919 is a deficient number, since it is larger than the sum of its proper divisors (309920001).

643679919 is a wasteful number, since it uses less digits than its factorization.

643679919 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23840006 (or 23840000 counting only the distinct ones).

The product of its digits is 2204496, while the sum is 54.

The square root of 643679919 is about 25370.8478179189. The cubic root of 643679919 is about 863.4224173101.

The spelling of 643679919 in words is "six hundred forty-three million, six hundred seventy-nine thousand, nine hundred nineteen".