81811251583 has 8 divisors (see below), whose sum is σ = 82437120000. Its totient is φ = 81187531128.

The previous prime is 81811251563. The next prime is 81811251607. The reversal of 81811251583 is 38515211818.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81811251583 - 2²¹ = 81809154431 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 (81811251523) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 460483 + ... + 612916.

It is an arithmetic number, because the mean of its divisors is an integer number (10304640000).

Almost surely, 2^81811251583 is an apocalyptic number.

81811251583 is a deficient number, since it is larger than the sum of its proper divisors (625868417).

81811251583 is a wasteful number, since it uses less digits than its factorization.

81811251583 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1073981.

The product of its digits is 76800, while the sum is 43.

The spelling of 81811251583 in words is "eighty-one billion, eight hundred eleven million, two hundred fifty-one thousand, five hundred eighty-three".