81220100202 has 24 divisors (see below), whose sum is σ = 176631083460. Its totient is φ = 26972720640.

The previous prime is 81220100197. The next prime is 81220100251. The reversal of 81220100202 is 20200102218.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 56193176601 + 25026923601 = 237051^2 + 158199^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8382199 + ... + 8391882.

Almost surely, 2^81220100202 is an apocalyptic number.

81220100202 is an abundant number, since it is smaller than the sum of its proper divisors (95410983258).

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

81220100202 is a wasteful number, since it uses less digits than its factorization.

81220100202 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16774358 (or 16774355 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

The spelling of 81220100202 in words is "eighty-one billion, two hundred twenty million, one hundred thousand, two hundred two".