81612993 has 32 divisors (see below), whose sum is σ = 141576192. Its totient is φ = 40550400.

The previous prime is 81612991. The next prime is 81612997. The reversal of 81612993 is 39921618.

It is not a de Polignac number, because 81612993 - 2¹ = 81612991 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81612991) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2368 + ... + 12993.

It is an arithmetic number, because the mean of its divisors is an integer number (4424256).

Almost surely, 2^81612993 is an apocalyptic number.

It is an amenable number.

81612993 is a deficient number, since it is larger than the sum of its proper divisors (59963199).

81612993 is a wasteful number, since it uses less digits than its factorization.

81612993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15405.

The product of its digits is 23328, while the sum is 39.

The square root of 81612993 is about 9033.9909785211. The cubic root of 81612993 is about 433.7635970346.

The spelling of 81612993 in words is "eighty-one million, six hundred twelve thousand, nine hundred ninety-three".