81377745624 has 96 divisors (see below), whose sum is σ = 258027063840. Its totient is φ = 22683686400.

The previous prime is 81377745623. The next prime is 81377745629. The reversal of 81377745624 is 42654777318.

81377745624 is a `hidden beast` number, since 8 + 1 + 3 + 7 + 7 + 7 + 4 + 5 + 624 = 666.

It is a super-2 number, since 2×81377745624² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81377745623) 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, 1948407 + ... + 1989734.

It is an arithmetic number, because the mean of its divisors is an integer number (2687781915).

Almost surely, 2^81377745624 is an apocalyptic number.

81377745624 is a gapful number since it is divisible by the number (84) formed by its first and last digit.

It is an amenable number.

81377745624 is an abundant number, since it is smaller than the sum of its proper divisors (176649318216).

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

81377745624 is a wasteful number, since it uses less digits than its factorization.

81377745624 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3938201 (or 3938194 counting only the distinct ones).

The product of its digits is 7902720, while the sum is 54.

The spelling of 81377745624 in words is "eighty-one billion, three hundred seventy-seven million, seven hundred forty-five thousand, six hundred twenty-four".