81435725 has 24 divisors (see below), whose sum is σ = 117873408. Its totient is φ = 54648000.

The previous prime is 81435721. The next prime is 81435737. The reversal of 81435725 is 52753418.

It is a happy number.

It is not a de Polignac number, because 81435725 - 2² = 81435721 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81435721) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3275 + ... + 13175.

It is an arithmetic number, because the mean of its divisors is an integer number (4911392).

Almost surely, 2^81435725 is an apocalyptic number.

It is an amenable number.

81435725 is a deficient number, since it is larger than the sum of its proper divisors (36437683).

81435725 is a wasteful number, since it uses less digits than its factorization.

81435725 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9965 (or 9960 counting only the distinct ones).

The product of its digits is 33600, while the sum is 35.

The square root of 81435725 is about 9024.1744774799. The cubic root of 81435725 is about 433.4493164227.

The spelling of 81435725 in words is "eighty-one million, four hundred thirty-five thousand, seven hundred twenty-five".