81645437337 has 4 divisors (see below), whose sum is σ = 108860583120. Its totient is φ = 54430291556.

The previous prime is 81645437323. The next prime is 81645437437. The reversal of 81645437337 is 73373454618.

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 81645437337 - 2¹⁸ = 81645175193 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81645437337.

It is not an unprimeable number, because it can be changed into a prime (81645437437) 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, 13607572887 + ... + 13607572892.

It is an arithmetic number, because the mean of its divisors is an integer number (27215145780).

Almost surely, 2^81645437337 is an apocalyptic number.

It is an amenable number.

81645437337 is a deficient number, since it is larger than the sum of its proper divisors (27215145783).

81645437337 is a wasteful number, since it uses less digits than its factorization.

81645437337 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27215145782.

The product of its digits is 5080320, while the sum is 51.

The spelling of 81645437337 in words is "eighty-one billion, six hundred forty-five million, four hundred thirty-seven thousand, three hundred thirty-seven".