81643254 has 64 divisors (see below), whose sum is σ = 206986752. Its totient is φ = 20851200.

The previous prime is 81643253. The next prime is 81643279. The reversal of 81643254 is 45234618.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81643253) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 26734 + ... + 29630.

It is an arithmetic number, because the mean of its divisors is an integer number (3234168).

Almost surely, 2^81643254 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81643254, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (103493376).

81643254 is an abundant number, since it is smaller than the sum of its proper divisors (125343498).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81643254 is a wasteful number, since it uses less digits than its factorization.

81643254 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2981.

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

The square root of 81643254 is about 9035.6656644655. The cubic root of 81643254 is about 433.8172016456.

The spelling of 81643254 in words is "eighty-one million, six hundred forty-three thousand, two hundred fifty-four".