641778833 has 4 divisors (see below), whose sum is σ = 662481408. Its totient is φ = 621076260.

The previous prime is 641778793. The next prime is 641778859. The reversal of 641778833 is 338877146.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 338877146 = 2 ⋅169438573.

It is a cyclic number.

It is not a de Polignac number, because 641778833 - 2²⁰ = 640730257 is a prime.

It is not an unprimeable number, because it can be changed into a prime (641771833) 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, 10351241 + ... + 10351302.

It is an arithmetic number, because the mean of its divisors is an integer number (165620352).

Almost surely, 2^641778833 is an apocalyptic number.

It is an amenable number.

641778833 is a deficient number, since it is larger than the sum of its proper divisors (20702575).

641778833 is a wasteful number, since it uses less digits than its factorization.

641778833 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20702574.

The product of its digits is 677376, while the sum is 47.

The square root of 641778833 is about 25333.3541600792. The cubic root of 641778833 is about 862.5715498439.

The spelling of 641778833 in words is "six hundred forty-one million, seven hundred seventy-eight thousand, eight hundred thirty-three".