81643450 has 24 divisors (see below), whose sum is σ = 173551392. Its totient is φ = 27991920.

The previous prime is 81643427. The next prime is 81643459. The reversal of 81643450 is 5434618.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (81643459) 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 11 ways as a sum of consecutive naturals, for example, 116284 + ... + 116983.

It is an arithmetic number, because the mean of its divisors is an integer number (7231308).

Almost surely, 2^81643450 is an apocalyptic number.

81643450 is an abundant number, since it is smaller than the sum of its proper divisors (91907942).

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

81643450 is a wasteful number, since it uses less digits than its factorization.

81643450 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 233286 (or 233281 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 31.

The square root of 81643450 is about 9035.6765103671. The cubic root of 81643450 is about 433.8175487986.

The spelling of 81643450 in words is "eighty-one million, six hundred forty-three thousand, four hundred fifty".