1640661437 has 8 divisors (see below), whose sum is σ = 1686060000. Its totient is φ = 1595318544.

The previous prime is 1640661427. The next prime is 1640661443. The reversal of 1640661437 is 7341660461.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1640661437 - 2⁸ = 1640661181 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1640661437.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1640661427) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 49814 + ... + 75912.

It is an arithmetic number, because the mean of its divisors is an integer number (210757500).

Almost surely, 2^1640661437 is an apocalyptic number.

It is an amenable number.

1640661437 is a deficient number, since it is larger than the sum of its proper divisors (45398563).

1640661437 is a wasteful number, since it uses less digits than its factorization.

1640661437 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27835.

The product of its (nonzero) digits is 72576, while the sum is 38.

The square root of 1640661437 is about 40505.0791506448. The cubic root of 1640661437 is about 1179.4322263727.

The spelling of 1640661437 in words is "one billion, six hundred forty million, six hundred sixty-one thousand, four hundred thirty-seven".