81962991 has 24 divisors (see below), whose sum is σ = 129482496. Its totient is φ = 49548240.

The previous prime is 81962989. The next prime is 81963067. The reversal of 81962991 is 19926918.

81962991 is a `hidden beast` number, since 8 + 19 + 629 + 9 + 1 = 666.

It is not a de Polignac number, because 81962991 - 2¹ = 81962989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81962911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 50986 + ... + 52568.

It is an arithmetic number, because the mean of its divisors is an integer number (5395104).

Almost surely, 2^81962991 is an apocalyptic number.

81962991 is a deficient number, since it is larger than the sum of its proper divisors (47519505).

81962991 is a wasteful number, since it uses less digits than its factorization.

81962991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2123 (or 2120 counting only the distinct ones).

The product of its digits is 69984, while the sum is 45.

The square root of 81962991 is about 9053.3414273405. The cubic root of 81962991 is about 434.3827790198.

The spelling of 81962991 in words is "eighty-one million, nine hundred sixty-two thousand, nine hundred ninety-one".