81616989 has 16 divisors (see below), whose sum is σ = 115692480. Its totient is φ = 51033600.

The previous prime is 81616981. The next prime is 81616999. The reversal of 81616989 is 98961618.

It is not a de Polignac number, because 81616989 - 2³ = 81616981 is a prime.

It is a super-2 number, since 2×81616989² = 13322665786852242, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81616981) 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, 1332 + ... + 12845.

It is an arithmetic number, because the mean of its divisors is an integer number (7230780).

Almost surely, 2^81616989 is an apocalyptic number.

It is an amenable number.

81616989 is a deficient number, since it is larger than the sum of its proper divisors (34075491).

81616989 is a wasteful number, since it uses less digits than its factorization.

81616989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14300.

The product of its digits is 186624, while the sum is 48.

The square root of 81616989 is about 9034.2121405245. The cubic root of 81616989 is about 433.7706763447.

The spelling of 81616989 in words is "eighty-one million, six hundred sixteen thousand, nine hundred eighty-nine".