81437642604 has 72 divisors (see below), whose sum is σ = 217174230000. Its totient is φ = 25659777024.

The previous prime is 81437642603. The next prime is 81437642609. The reversal of 81437642604 is 40624673418.

81437642604 is a `hidden beast` number, since 8 + 1 + 4 + 37 + 6 + 4 + 2 + 604 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 81437642604.

It is not an unprimeable number, because it can be changed into a prime (81437642603) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 174532 + ... + 439700.

It is an arithmetic number, because the mean of its divisors is an integer number (3016308750).

Almost surely, 2^81437642604 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81437642604, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (108587115000).

81437642604 is an abundant number, since it is smaller than the sum of its proper divisors (135736587396).

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

81437642604 is a wasteful number, since it uses less digits than its factorization.

81437642604 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 265647 (or 265642 counting only the distinct ones).

The product of its (nonzero) digits is 774144, while the sum is 45.

The spelling of 81437642604 in words is "eighty-one billion, four hundred thirty-seven million, six hundred forty-two thousand, six hundred four".