81990126 has 24 divisors (see below), whose sum is σ = 178026264. Its totient is φ = 27271440.

The previous prime is 81990107. The next prime is 81990143. The reversal of 81990126 is 62109918.

It is a super-2 number, since 2×81990126² = 13444761522991752, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4200 + ... + 13476.

It is an arithmetic number, because the mean of its divisors is an integer number (7417761).

Almost surely, 2^81990126 is an apocalyptic number.

81990126 is an abundant number, since it is smaller than the sum of its proper divisors (96036138).

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

81990126 is a wasteful number, since it uses less digits than its factorization.

81990126 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9776 (or 9773 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 36.

The square root of 81990126 is about 9054.8399212797. The cubic root of 81990126 is about 434.4307099053.

The spelling of 81990126 in words is "eighty-one million, nine hundred ninety thousand, one hundred twenty-six".