639542391900 has 144 divisors (see below), whose sum is σ = 1977569427456. Its totient is φ = 159012346880.

The previous prime is 639542391889. The next prime is 639542391913. The reversal of 639542391900 is 9193245936.

It is a super-2 number, since 2×639542391900² (a number of 24 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 40284 + ... + 1131683.

It is an arithmetic number, because the mean of its divisors is an integer number (13733121024).

Almost surely, 2^639542391900 is an apocalyptic number.

639542391900 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 639542391900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (988784713728).

639542391900 is an abundant number, since it is smaller than the sum of its proper divisors (1338027035556).

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

639542391900 is a wasteful number, since it uses less digits than its factorization.

639542391900 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1172108 (or 1172101 counting only the distinct ones).

The product of its (nonzero) digits is 1574640, while the sum is 51.

The spelling of 639542391900 in words is "six hundred thirty-nine billion, five hundred forty-two million, three hundred ninety-one thousand, nine hundred".