81657725629 has 4 divisors (see below), whose sum is σ = 82044729280. Its totient is φ = 81270721980.

The previous prime is 81657725587. The next prime is 81657725657. The reversal of 81657725629 is 92652775618.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81657725629 - 2⁹ = 81657725117 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81657725729) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 193501509 + ... + 193501930.

It is an arithmetic number, because the mean of its divisors is an integer number (20511182320).

Almost surely, 2^81657725629 is an apocalyptic number.

It is an amenable number.

81657725629 is a deficient number, since it is larger than the sum of its proper divisors (387003651).

81657725629 is a wasteful number, since it uses less digits than its factorization.

81657725629 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 387003650.

The product of its digits is 12700800, while the sum is 58.

The spelling of 81657725629 in words is "eighty-one billion, six hundred fifty-seven million, seven hundred twenty-five thousand, six hundred twenty-nine".