81947151 has 48 divisors (see below), whose sum is σ = 142545312. Its totient is φ = 44697600.

The previous prime is 81947149. The next prime is 81947189. The reversal of 81947151 is 15174918.

It is not a de Polignac number, because 81947151 - 2¹ = 81947149 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81947101) 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 47 ways as a sum of consecutive naturals, for example, 51991 + ... + 53543.

It is an arithmetic number, because the mean of its divisors is an integer number (2969694).

Almost surely, 2^81947151 is an apocalyptic number.

81947151 is a deficient number, since it is larger than the sum of its proper divisors (60598161).

81947151 is a wasteful number, since it uses less digits than its factorization.

81947151 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1624 (or 1621 counting only the distinct ones).

The product of its digits is 10080, while the sum is 36.

The square root of 81947151 is about 9052.4665699466. The cubic root of 81947151 is about 434.3547945745.

The spelling of 81947151 in words is "eighty-one million, nine hundred forty-seven thousand, one hundred fifty-one".