81642925 has 48 divisors (see below), whose sum is σ = 131991552. Its totient is φ = 48614400.

The previous prime is 81642923. The next prime is 81642929. The reversal of 81642925 is 52924618.

It is not a de Polignac number, because 81642925 - 2¹ = 81642923 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81642923) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 37620 + ... + 39730.

It is an arithmetic number, because the mean of its divisors is an integer number (2749824).

Almost surely, 2^81642925 is an apocalyptic number.

81642925 is a gapful number since it is divisible by the number (85) formed by its first and last digit.

It is an amenable number.

81642925 is a deficient number, since it is larger than the sum of its proper divisors (50348627).

81642925 is a wasteful number, since it uses less digits than its factorization.

81642925 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2158 (or 2153 counting only the distinct ones).

The product of its digits is 34560, while the sum is 37.

The square root of 81642925 is about 9035.6474588156. The cubic root of 81642925 is about 433.8166189232.

The spelling of 81642925 in words is "eighty-one million, six hundred forty-two thousand, nine hundred twenty-five".