81520190 has 16 divisors (see below), whose sum is σ = 146903328. Its totient is φ = 32570976.

The previous prime is 81520171. The next prime is 81520199. The reversal of 81520190 is 9102518.

It is a happy number.

It is a super-2 number, since 2×81520190² = 13291082755272200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81520199) 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 7 ways as a sum of consecutive naturals, for example, 5684 + ... + 13976.

It is an arithmetic number, because the mean of its divisors is an integer number (9181458).

Almost surely, 2^81520190 is an apocalyptic number.

81520190 is a deficient number, since it is larger than the sum of its proper divisors (65383138).

81520190 is a wasteful number, since it uses less digits than its factorization.

81520190 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9283.

The product of its (nonzero) digits is 720, while the sum is 26.

The square root of 81520190 is about 9028.8531940662. The cubic root of 81520190 is about 433.5991222812.

The spelling of 81520190 in words is "eighty-one million, five hundred twenty thousand, one hundred ninety".