81871740 has 36 divisors (see below), whose sum is σ = 248344824. Its totient is φ = 21832416.

The previous prime is 81871739. The next prime is 81871819. The reversal of 81871740 is 4717818.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 81871695 and 81871704.

It is a congruent number.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 227242 + ... + 227601.

Almost surely, 2^81871740 is an apocalyptic number.

It is an amenable number.

81871740 is an abundant number, since it is smaller than the sum of its proper divisors (166473084).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81871740 is a wasteful number, since it uses less digits than its factorization.

81871740 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 454858 (or 454853 counting only the distinct ones).

The product of its (nonzero) digits is 12544, while the sum is 36.

The square root of 81871740 is about 9048.3003928915. The cubic root of 81871740 is about 434.2215168800.

The spelling of 81871740 in words is "eighty-one million, eight hundred seventy-one thousand, seven hundred forty".