81951945 has 8 divisors (see below), whose sum is σ = 131123136. Its totient is φ = 43707696.

The previous prime is 81951943. The next prime is 81951949. The reversal of 81951945 is 54915918.

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

It is not a de Polignac number, because 81951945 - 2¹ = 81951943 is a prime.

It is a super-2 number, since 2×81951945² = 13432242578566050, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81951897 and 81951906.

It is not an unprimeable number, because it can be changed into a prime (81951943) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2731717 + ... + 2731746.

It is an arithmetic number, because the mean of its divisors is an integer number (16390392).

Almost surely, 2^81951945 is an apocalyptic number.

It is an amenable number.

81951945 is a deficient number, since it is larger than the sum of its proper divisors (49171191).

81951945 is a wasteful number, since it uses less digits than its factorization.

81951945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5463471.

The product of its digits is 64800, while the sum is 42.

The square root of 81951945 is about 9052.7313557843. The cubic root of 81951945 is about 434.3632644898.

The spelling of 81951945 in words is "eighty-one million, nine hundred fifty-one thousand, nine hundred forty-five".