6640725437 has 4 divisors (see below), whose sum is σ = 6658247520. Its totient is φ = 6623203356.

The previous prime is 6640725431. The next prime is 6640725451. The reversal of 6640725437 is 7345270466.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 6640725437 - 2²⁶ = 6573616573 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6640725431) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8760473 + ... + 8761230.

It is an arithmetic number, because the mean of its divisors is an integer number (1664561880).

Almost surely, 2^6640725437 is an apocalyptic number.

It is an amenable number.

6640725437 is a deficient number, since it is larger than the sum of its proper divisors (17522083).

6640725437 is a wasteful number, since it uses less digits than its factorization.

6640725437 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17522082.

The product of its (nonzero) digits is 846720, while the sum is 44.

The square root of 6640725437 is about 81490.6463160037. The cubic root of 6640725437 is about 1879.6277213856.

The spelling of 6640725437 in words is "six billion, six hundred forty million, seven hundred twenty-five thousand, four hundred thirty-seven".