81644235 has 32 divisors (see below), whose sum is σ = 141957120. Its totient is φ = 39916800.

The previous prime is 81644219. The next prime is 81644261. The reversal of 81644235 is 53244618.

It is not a de Polignac number, because 81644235 - 2⁴ = 81644219 is a prime.

It is a super-2 number, since 2×81644235² = 13331562217470450, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81644196 and 81644205.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4215 + ... + 13455.

It is an arithmetic number, because the mean of its divisors is an integer number (4436160).

Almost surely, 2^81644235 is an apocalyptic number.

81644235 is a deficient number, since it is larger than the sum of its proper divisors (60312885).

81644235 is a wasteful number, since it uses less digits than its factorization.

81644235 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9299.

The product of its digits is 23040, while the sum is 33.

The square root of 81644235 is about 9035.7199491795. The cubic root of 81644235 is about 433.8189391762.

The spelling of 81644235 in words is "eighty-one million, six hundred forty-four thousand, two hundred thirty-five".