81681617626 has 16 divisors (see below), whose sum is σ = 143004900096. Its totient is φ = 34261590096.

The previous prime is 81681617569. The next prime is 81681617639. The reversal of 81681617626 is 62671618618.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 62067441 + ... + 62068756.

It is an arithmetic number, because the mean of its divisors is an integer number (8937806256).

Almost surely, 2^81681617626 is an apocalyptic number.

81681617626 is a deficient number, since it is larger than the sum of its proper divisors (61323282470).

81681617626 is a wasteful number, since it uses less digits than its factorization.

81681617626 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 124136253.

The product of its digits is 1161216, while the sum is 52.

The spelling of 81681617626 in words is "eighty-one billion, six hundred eighty-one million, six hundred seventeen thousand, six hundred twenty-six".