640423548 has 18 divisors (see below), whose sum is σ = 1618848504. Its totient is φ = 213474504.

The previous prime is 640423429. The next prime is 640423549. The reversal of 640423548 is 845324046.

640423548 is a `hidden beast` number, since 640 + 4 + 2 + 3 + 5 + 4 + 8 = 666.

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

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: 17789543 = 640423548 / (6 + 4 + 0 + 4 + 2 + 3 + 5 + 4 + 8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640423549) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 8894736 + ... + 8894807.

It is an arithmetic number, because the mean of its divisors is an integer number (89936028).

Almost surely, 2^640423548 is an apocalyptic number.

It is an amenable number.

640423548 is an abundant number, since it is smaller than the sum of its proper divisors (978424956).

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

640423548 is a wasteful number, since it uses less digits than its factorization.

640423548 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17789553 (or 17789548 counting only the distinct ones).

The product of its (nonzero) digits is 92160, while the sum is 36.

The square root of 640423548 is about 25306.5909991844. The cubic root of 640423548 is about 861.9639396130.

The spelling of 640423548 in words is "six hundred forty million, four hundred twenty-three thousand, five hundred forty-eight".