81556445250 has 288 divisors, whose sum is σ = 263479812336. Its totient is φ = 18136742400.

The previous prime is 81556445239. The next prime is 81556445261. The reversal of 81556445250 is 5254465518.

81556445250 is a `hidden beast` number, since 8 + 1 + 556 + 4 + 45 + 2 + 50 = 666.

It is an interprime number because it is at equal distance from previous prime (81556445239) and next prime (81556445261).

It can be written as a sum of positive squares in 8 ways, for example, as 15670282761 + 65886162489 = 125181^2 + 256683^2 .

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a junction number, because it is equal to n+sod(n) for n = 81556445196 and 81556445205.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 4069254 + ... + 4089246.

Almost surely, 2^81556445250 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81556445250, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (131739906168).

81556445250 is an abundant number, since it is smaller than the sum of its proper divisors (181923367086).

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

81556445250 is a wasteful number, since it uses less digits than its factorization.

81556445250 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20067 (or 20047 counting only the distinct ones).

The product of its (nonzero) digits is 960000, while the sum is 45.

The spelling of 81556445250 in words is "eighty-one billion, five hundred fifty-six million, four hundred forty-five thousand, two hundred fifty".