81797990450 has 54 divisors (see below), whose sum is σ = 167278442583. Its totient is φ = 29736634400.

The previous prime is 81797990447. The next prime is 81797990473. The reversal of 81797990450 is 5409979718.

It can be written as a sum of positive squares in 5 ways, for example, as 55118361529 + 26679628921 = 234773^2 + 163339^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=202235.

It is a super-2 number, since 2×81797990450² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 81797990450.

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 22244012 + ... + 22247688.

Almost surely, 2^81797990450 is an apocalyptic number.

81797990450 is an abundant number, since it is smaller than the sum of its proper divisors (85480452133).

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

81797990450 is an equidigital number, since it uses as much as digits as its factorization.

81797990450 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7388 (or 3695 counting only the distinct ones).

The product of its (nonzero) digits is 5715360, while the sum is 59.

The spelling of 81797990450 in words is "eighty-one billion, seven hundred ninety-seven million, nine hundred ninety thousand, four hundred fifty".