81725810 has 16 divisors (see below), whose sum is σ = 147284352. Its totient is φ = 32650800.

The previous prime is 81725807. The next prime is 81725849. The reversal of 81725810 is 1852718.

It is a happy number.

It is a super-2 number, since 2×81725810² = 13358216040312200, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4625 + ... + 13595.

It is an arithmetic number, because the mean of its divisors is an integer number (9205272).

Almost surely, 2^81725810 is an apocalyptic number.

81725810 is a deficient number, since it is larger than the sum of its proper divisors (65558542).

81725810 is a wasteful number, since it uses less digits than its factorization.

81725810 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9889.

The product of its (nonzero) digits is 4480, while the sum is 32.

The square root of 81725810 is about 9040.2328509834. The cubic root of 81725810 is about 433.9633747682.

The spelling of 81725810 in words is "eighty-one million, seven hundred twenty-five thousand, eight hundred ten".