640432532138 has 32 divisors (see below), whose sum is σ = 1099252028160. Its totient is φ = 274129390080.

The previous prime is 640432532137. The next prime is 640432532153. The reversal of 640432532138 is 831235234046.

It is a happy number.

It is a super-4 number, since 4×640432532138⁴ (a number of 48 digits) contains 4444 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 640432532095 and 640432532104.

It is not an unprimeable number, because it can be changed into a prime (640432532137) 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, 41624795 + ... + 41640177.

It is an arithmetic number, because the mean of its divisors is an integer number (34351625880).

Almost surely, 2^640432532138 is an apocalyptic number.

640432532138 is a deficient number, since it is larger than the sum of its proper divisors (458819496022).

640432532138 is a wasteful number, since it uses less digits than its factorization.

640432532138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18902.

The product of its (nonzero) digits is 414720, while the sum is 41.

The spelling of 640432532138 in words is "six hundred forty billion, four hundred thirty-two million, five hundred thirty-two thousand, one hundred thirty-eight".