81616900 has 18 divisors (see below), whose sum is σ = 177108890. Its totient is φ = 32646720.

The previous prime is 81616897. The next prime is 81616907. The reversal of 81616900 is 961618.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 5299204 + 76317696 = 2302^2 + 8736^2 .

It is a super-2 number, since 2×81616900² = 13322636731220000, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81616907) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 407985 + ... + 408184.

Almost surely, 2^81616900 is an apocalyptic number.

It is an amenable number.

81616900 is an abundant number, since it is smaller than the sum of its proper divisors (95491990).

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

81616900 is a wasteful number, since it uses less digits than its factorization.

81616900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 816183 (or 816176 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 31.

The square root of 81616900 is about 9034.2072148031. The cubic root of 81616900 is about 433.7705186749.

The spelling of 81616900 in words is "eighty-one million, six hundred sixteen thousand, nine hundred".