81321634 has 16 divisors (see below), whose sum is σ = 131875200. Its totient is φ = 37479024.

The previous prime is 81321619. The next prime is 81321637. The reversal of 81321634 is 43612318.

It is a super-2 number, since 2×81321634² = 13226416312859912, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81321637) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27514 + ... + 30325.

It is an arithmetic number, because the mean of its divisors is an integer number (8242200).

Almost surely, 2^81321634 is an apocalyptic number.

81321634 is a deficient number, since it is larger than the sum of its proper divisors (50553566).

81321634 is a wasteful number, since it uses less digits than its factorization.

81321634 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57897.

The product of its digits is 3456, while the sum is 28.

The square root of 81321634 is about 9017.8508526145. The cubic root of 81321634 is about 433.2468017882.

The spelling of 81321634 in words is "eighty-one million, three hundred twenty-one thousand, six hundred thirty-four".