81942291 has 24 divisors (see below), whose sum is σ = 121465344. Its totient is φ = 53207280.

The previous prime is 81942283. The next prime is 81942299. The reversal of 81942291 is 19224918.

It is an interprime number because it is at equal distance from previous prime (81942283) and next prime (81942299).

It is not a de Polignac number, because 81942291 - 2³ = 81942283 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81942299) 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 23 ways as a sum of consecutive naturals, for example, 129546 + ... + 130176.

It is an arithmetic number, because the mean of its divisors is an integer number (5061056).

Almost surely, 2^81942291 is an apocalyptic number.

81942291 is a deficient number, since it is larger than the sum of its proper divisors (39523053).

81942291 is a wasteful number, since it uses less digits than its factorization.

81942291 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 991 (or 988 counting only the distinct ones).

The product of its digits is 10368, while the sum is 36.

The square root of 81942291 is about 9052.1981308409. The cubic root of 81942291 is about 434.3462077149.

The spelling of 81942291 in words is "eighty-one million, nine hundred forty-two thousand, two hundred ninety-one".