1640642436 has 18 divisors (see below), whose sum is σ = 4147179582. Its totient is φ = 546880800.

The previous prime is 1640642413. The next prime is 1640642447. The reversal of 1640642436 is 6342460461.

1640642436 is a `hidden beast` number, since 1 + 6 + 4 + 0 + 642 + 4 + 3 + 6 = 666.

It can be written as a sum of positive squares in only one way, i.e., 1485639936 + 155002500 = 38544^2 + 12450^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a super-3 number, since 3×1640642436³ (a number of 29 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 45573401 = 1640642436 / (1 + 6 + 4 + 0 + 6 + 4 + 2 + 4 + 3 + 6).

It is a self number, because there is not a number n which added to its sum of digits gives 1640642436.

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, 22786665 + ... + 22786736.

Almost surely, 2^1640642436 is an apocalyptic number.

It is an amenable number.

1640642436 is an abundant number, since it is smaller than the sum of its proper divisors (2506537146).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1640642436 is a wasteful number, since it uses less digits than its factorization.

1640642436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45573411 (or 45573406 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 36.

The square root of 1640642436 is about 40504.8445991341. The cubic root of 1640642436 is about 1179.4276732338.

The spelling of 1640642436 in words is "one billion, six hundred forty million, six hundred forty-two thousand, four hundred thirty-six".