640436162531 has 32 divisors (see below), whose sum is σ = 781461976320. Its totient is φ = 517278182400.

The previous prime is 640436162521. The next prime is 640436162537. The reversal of 640436162531 is 135261634046.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-640436162531 is a prime.

It is a super-2 number, since 2×640436162531² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640436162537) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 677660 + ... + 1319126.

It is an arithmetic number, because the mean of its divisors is an integer number (24420686760).

Almost surely, 2^640436162531 is an apocalyptic number.

640436162531 is a deficient number, since it is larger than the sum of its proper divisors (141025813789).

640436162531 is a wasteful number, since it uses less digits than its factorization.

640436162531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 641795.

The product of its (nonzero) digits is 311040, while the sum is 41.

Adding to 640436162531 its reverse (135261634046), we get a palindrome (775697796577).

The spelling of 640436162531 in words is "six hundred forty billion, four hundred thirty-six million, one hundred sixty-two thousand, five hundred thirty-one".