81555198 has 16 divisors (see below), whose sum is σ = 163831680. Its totient is φ = 27064856.

The previous prime is 81555197. The next prime is 81555233. The reversal of 81555198 is 89155518.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81555197) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28578 + ... + 31301.

It is an arithmetic number, because the mean of its divisors is an integer number (10239480).

Almost surely, 2^81555198 is an apocalyptic number.

81555198 is an abundant number, since it is smaller than the sum of its proper divisors (82276482).

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

81555198 is a wasteful number, since it uses less digits than its factorization.

81555198 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60111.

The product of its digits is 72000, while the sum is 42.

The square root of 81555198 is about 9030.7916596498. The cubic root of 81555198 is about 433.6611816136.

The spelling of 81555198 in words is "eighty-one million, five hundred fifty-five thousand, one hundred ninety-eight".