638660261020 has 24 divisors (see below), whose sum is σ = 1357345425744. Its totient is φ = 252386222976.

The previous prime is 638660261011. The next prime is 638660261047. The reversal of 638660261020 is 20162066836.

It is a happy number.

It is a super-2 number, since 2×638660261020² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 192365889 + ... + 192369208.

It is an arithmetic number, because the mean of its divisors is an integer number (56556059406).

Almost surely, 2^638660261020 is an apocalyptic number.

It is an amenable number.

638660261020 is an abundant number, since it is smaller than the sum of its proper divisors (718685164724).

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

638660261020 is a wasteful number, since it uses less digits than its factorization.

638660261020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 384735189 (or 384735187 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 40.

The spelling of 638660261020 in words is "six hundred thirty-eight billion, six hundred sixty million, two hundred sixty-one thousand, twenty".