81925666 has 8 divisors (see below), whose sum is σ = 123425820. Its totient is φ = 40783728.

The previous prime is 81925661. The next prime is 81925673. The reversal of 81925666 is 66652918.

It can be written as a sum of positive squares in 2 ways, for example, as 76930441 + 4995225 = 8771^2 + 2235^2 .

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

It is not an unprimeable number, because it can be changed into a prime (81925661) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 88981 + ... + 89896.

Almost surely, 2^81925666 is an apocalyptic number.

81925666 is a deficient number, since it is larger than the sum of its proper divisors (41500154).

81925666 is a wasteful number, since it uses less digits than its factorization.

81925666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 179108.

The product of its digits is 155520, while the sum is 43.

The square root of 81925666 is about 9051.2797990119. The cubic root of 81925666 is about 434.3168313737.

The spelling of 81925666 in words is "eighty-one million, nine hundred twenty-five thousand, six hundred sixty-six".