81961157 has 8 divisors (see below), whose sum is σ = 83207040. Its totient is φ = 80720640.

The previous prime is 81961129. The next prime is 81961169. The reversal of 81961157 is 75116918.

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

It is a cyclic number.

It is not a de Polignac number, because 81961157 - 2⁶ = 81961093 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81961157.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81961177) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 37733 + ... + 39845.

It is an arithmetic number, because the mean of its divisors is an integer number (10400880).

Almost surely, 2^81961157 is an apocalyptic number.

It is an amenable number.

81961157 is a deficient number, since it is larger than the sum of its proper divisors (1245883).

81961157 is a wasteful number, since it uses less digits than its factorization.

81961157 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2683.

The product of its digits is 15120, while the sum is 38.

The square root of 81961157 is about 9053.2401382047. The cubic root of 81961157 is about 434.3795390862.

The spelling of 81961157 in words is "eighty-one million, nine hundred sixty-one thousand, one hundred fifty-seven".