81979125 has 16 divisors (see below), whose sum is σ = 136413888. Its totient is φ = 43722000.

The previous prime is 81979109. The next prime is 81979133. The reversal of 81979125 is 52197918.

It is not a de Polignac number, because 81979125 - 2⁴ = 81979109 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 108931 + ... + 109680.

It is an arithmetic number, because the mean of its divisors is an integer number (8525868).

Almost surely, 2^81979125 is an apocalyptic number.

It is an amenable number.

81979125 is a deficient number, since it is larger than the sum of its proper divisors (54434763).

81979125 is a wasteful number, since it uses less digits than its factorization.

81979125 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 218629 (or 218619 counting only the distinct ones).

The product of its digits is 45360, while the sum is 42.

The square root of 81979125 is about 9054.2324357176. The cubic root of 81979125 is about 434.4112791671.

The spelling of 81979125 in words is "eighty-one million, nine hundred seventy-nine thousand, one hundred twenty-five".