640643635620404 has 18 divisors (see below), whose sum is σ = 1214000735548230. Its totient is φ = 295681677978336.

The previous prime is 640643635620349. The next prime is 640643635620431. The reversal of 640643635620404 is 404026536346046.

It can be written as a sum of positive squares in 3 ways, for example, as 708462256804 + 639935173363600 = 841702^2 + 25296940^2 .

It is a super-2 number, since 2×640643635620404² (a number of 30 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 473848842239 + ... + 473848843590.

It is an arithmetic number, because the mean of its divisors is an integer number (67444485308235).

Almost surely, 2^{640643635620404} is an apocalyptic number.

It is an amenable number.

640643635620404 is a deficient number, since it is larger than the sum of its proper divisors (573357099927826).

640643635620404 is a wasteful number, since it uses less digits than its factorization.

640643635620404 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 947697685859 (or 947697685844 counting only the distinct ones).

The product of its (nonzero) digits is 29859840, while the sum is 53.

The spelling of 640643635620404 in words is "six hundred forty trillion, six hundred forty-three billion, six hundred thirty-five million, six hundred twenty thousand, four hundred four".