81935400990 has 128 divisors (see below), whose sum is σ = 213805163520. Its totient is φ = 20018608128.

The previous prime is 81935400983. The next prime is 81935401001. The reversal of 81935400990 is 9900453918.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3086052 + ... + 3112488.

It is an arithmetic number, because the mean of its divisors is an integer number (1670352840).

Almost surely, 2^81935400990 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81935400990, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (106902581760).

81935400990 is an abundant number, since it is smaller than the sum of its proper divisors (131869762530).

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

81935400990 is a wasteful number, since it uses less digits than its factorization.

81935400990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26626.

The product of its (nonzero) digits is 349920, while the sum is 48.

The spelling of 81935400990 in words is "eighty-one billion, nine hundred thirty-five million, four hundred thousand, nine hundred ninety".