81593857969 has 16 divisors (see below), whose sum is σ = 90314375760. Its totient is φ = 73250242560.

The previous prime is 81593857949. The next prime is 81593857991. The reversal of 81593857969 is 96975839518.

It can be written as a sum of positive squares in 8 ways, for example, as 18196661025 + 63397196944 = 134895^2 + 251788^2 .

It is a cyclic number.

It is not a de Polignac number, because 81593857969 - 2⁷ = 81593857841 is a prime.

It is a super-2 number, since 2×81593857969² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81593857898 and 81593857907.

It is not an unprimeable number, because it can be changed into a prime (81593857949) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 507472 + ... + 648625.

It is an arithmetic number, because the mean of its divisors is an integer number (5644648485).

Almost surely, 2^81593857969 is an apocalyptic number.

81593857969 is a gapful number since it is divisible by the number (89) formed by its first and last digit.

It is an amenable number.

81593857969 is a deficient number, since it is larger than the sum of its proper divisors (8720517791).

81593857969 is a wasteful number, since it uses less digits than its factorization.

81593857969 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1156260.

The product of its digits is 146966400, while the sum is 70.

The spelling of 81593857969 in words is "eighty-one billion, five hundred ninety-three million, eight hundred fifty-seven thousand, nine hundred sixty-nine".