81251988 has 24 divisors (see below), whose sum is σ = 190300320. Its totient is φ = 26982240.

The previous prime is 81251981. The next prime is 81252001. The reversal of 81251988 is 88915218.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81251981) 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, 9358 + ... + 15813.

It is an arithmetic number, because the mean of its divisors is an integer number (7929180).

Almost surely, 2^81251988 is an apocalyptic number.

It is an amenable number.

81251988 is an abundant number, since it is smaller than the sum of its proper divisors (109048332).

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

81251988 is a wasteful number, since it uses less digits than its factorization.

81251988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25447 (or 25445 counting only the distinct ones).

The product of its digits is 46080, while the sum is 42.

The square root of 81251988 is about 9013.9884623845. The cubic root of 81251988 is about 433.1230851203.

The spelling of 81251988 in words is "eighty-one million, two hundred fifty-one thousand, nine hundred eighty-eight".