81311051 has 8 divisors (see below), whose sum is σ = 90625680. Its totient is φ = 72499968.

The previous prime is 81311011. The next prime is 81311059. The reversal of 81311051 is 15011318.

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

It is not a de Polignac number, because 81311051 - 2¹⁴ = 81294667 is a prime.

It is a super-2 number, since 2×81311051² = 13222974029449202, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81311059) 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, 125546 + ... + 126191.

It is an arithmetic number, because the mean of its divisors is an integer number (11328210).

Almost surely, 2^81311051 is an apocalyptic number.

81311051 is a deficient number, since it is larger than the sum of its proper divisors (9314629).

81311051 is a wasteful number, since it uses less digits than its factorization.

81311051 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 251773.

The product of its (nonzero) digits is 120, while the sum is 20.

The square root of 81311051 is about 9017.2640529154. The cubic root of 81311051 is about 433.2280070773.

Adding to 81311051 its reverse (15011318), we get a palindrome (96322369).

The spelling of 81311051 in words is "eighty-one million, three hundred eleven thousand, fifty-one".