81520194 has 16 divisors (see below), whose sum is σ = 186331968. Its totient is φ = 23291472.

The previous prime is 81520171. The next prime is 81520199. The reversal of 81520194 is 49102518.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (81520199) 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, 970437 + ... + 970520.

It is an arithmetic number, because the mean of its divisors is an integer number (11645748).

Almost surely, 2^81520194 is an apocalyptic number.

81520194 is an abundant number, since it is smaller than the sum of its proper divisors (104811774).

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

81520194 is a wasteful number, since it uses less digits than its factorization.

81520194 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1940969.

The product of its (nonzero) digits is 2880, while the sum is 30.

The square root of 81520194 is about 9028.8534155783. The cubic root of 81520194 is about 433.5991293731.

The spelling of 81520194 in words is "eighty-one million, five hundred twenty thousand, one hundred ninety-four".