31198021638 has 128 divisors (see below), whose sum is σ = 75039360000. Its totient is φ = 8461905408.

The previous prime is 31198021619. The next prime is 31198021643. The reversal of 31198021638 is 83612089113.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 31198021638.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 11347488 + ... + 11350236.

It is an arithmetic number, because the mean of its divisors is an integer number (586245000).

Almost surely, 2^31198021638 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31198021638, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37519680000).

31198021638 is an abundant number, since it is smaller than the sum of its proper divisors (43841338362).

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

31198021638 is a wasteful number, since it uses less digits than its factorization.

31198021638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2974.

The product of its (nonzero) digits is 62208, while the sum is 42.

The spelling of 31198021638 in words is "thirty-one billion, one hundred ninety-eight million, twenty-one thousand, six hundred thirty-eight".