81801288 has 24 divisors (see below), whose sum is σ = 221545350. Its totient is φ = 27267072.

The previous prime is 81801277. The next prime is 81801299. The reversal of 81801288 is 88210818.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (81801277) and next prime (81801299).

It can be written as a sum of positive squares in only one way, i.e., 52446564 + 29354724 = 7242^2 + 5418^2 .

It is a tau number, because it is divible by the number of its divisors (24).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 567993 + ... + 568136.

Almost surely, 2^81801288 is an apocalyptic number.

It is an amenable number.

81801288 is an abundant number, since it is smaller than the sum of its proper divisors (139744062).

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

81801288 is a wasteful number, since it uses less digits than its factorization.

81801288 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1136141 (or 1136134 counting only the distinct ones).

The product of its (nonzero) digits is 8192, while the sum is 36.

The square root of 81801288 is about 9044.4064481866. The cubic root of 81801288 is about 434.0969295136.

The spelling of 81801288 in words is "eighty-one million, eight hundred one thousand, two hundred eighty-eight".