81358989 has 4 divisors (see below), whose sum is σ = 108478656. Its totient is φ = 54239324.

The previous prime is 81358943. The next prime is 81358997. The reversal of 81358989 is 98985318.

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 81358989 - 2⁸ = 81358733 is a prime.

It is a super-2 number, since 2×81358989² = 13238570182204242, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81358909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13559829 + ... + 13559834.

It is an arithmetic number, because the mean of its divisors is an integer number (27119664).

Almost surely, 2^81358989 is an apocalyptic number.

It is an amenable number.

81358989 is a deficient number, since it is larger than the sum of its proper divisors (27119667).

81358989 is a wasteful number, since it uses less digits than its factorization.

81358989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27119666.

The product of its digits is 622080, while the sum is 51.

The square root of 81358989 is about 9019.9217845833. The cubic root of 81358989 is about 433.3131287753.

The spelling of 81358989 in words is "eighty-one million, three hundred fifty-eight thousand, nine hundred eighty-nine".