81687825 has 24 divisors (see below), whose sum is σ = 150064800. Its totient is φ = 43566480.

The previous prime is 81687811. The next prime is 81687841. The reversal of 81687825 is 52878618.

It is not a de Polignac number, because 81687825 - 2⁸ = 81687569 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 59835 + ... + 61184.

It is an arithmetic number, because the mean of its divisors is an integer number (6252700).

Almost surely, 2^81687825 is an apocalyptic number.

It is an amenable number.

81687825 is a deficient number, since it is larger than the sum of its proper divisors (68376975).

81687825 is a wasteful number, since it uses less digits than its factorization.

81687825 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 121038 (or 121027 counting only the distinct ones).

The product of its digits is 215040, while the sum is 45.

The square root of 81687825 is about 9038.1317206600. The cubic root of 81687825 is about 433.8961310040.

The spelling of 81687825 in words is "eighty-one million, six hundred eighty-seven thousand, eight hundred twenty-five".