640443051 has 16 divisors (see below), whose sum is σ = 998742400. Its totient is φ = 404490024.

The previous prime is 640443049. The next prime is 640443061. The reversal of 640443051 is 150344046.

It is not a de Polignac number, because 640443051 - 2¹ = 640443049 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640443031) 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, 623701 + ... + 624726.

It is an arithmetic number, because the mean of its divisors is an integer number (62421400).

Almost surely, 2^640443051 is an apocalyptic number.

640443051 is a deficient number, since it is larger than the sum of its proper divisors (358299349).

640443051 is a wasteful number, since it uses less digits than its factorization.

640443051 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1248455 (or 1248449 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 27.

The square root of 640443051 is about 25306.9763306484. The cubic root of 640443051 is about 861.9726894016.

Adding to 640443051 its reverse (150344046), we get a palindrome (790787097).

It can be divided in two parts, 6404 and 43051, that added together give a triangular number (49455 = T₃₁₄).

The spelling of 640443051 in words is "six hundred forty million, four hundred forty-three thousand, fifty-one".