640879142 has 4 divisors (see below), whose sum is σ = 961318716. Its totient is φ = 320439570.

The previous prime is 640879123. The next prime is 640879147. The reversal of 640879142 is 241978046.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 241978046 = 2 ⋅120989023.

It is a self number, because there is not a number n which added to its sum of digits gives 640879142.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640879147) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160219784 + ... + 160219787.

It is an arithmetic number, because the mean of its divisors is an integer number (240329679).

Almost surely, 2^640879142 is an apocalyptic number.

640879142 is a deficient number, since it is larger than the sum of its proper divisors (320439574).

640879142 is a wasteful number, since it uses less digits than its factorization.

640879142 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 320439573.

The product of its (nonzero) digits is 96768, while the sum is 41.

The square root of 640879142 is about 25315.5908878304. The cubic root of 640879142 is about 862.1682900590.

The spelling of 640879142 in words is "six hundred forty million, eight hundred seventy-nine thousand, one hundred forty-two".