81898772 has 6 divisors (see below), whose sum is σ = 143322858. Its totient is φ = 40949384.

The previous prime is 81898693. The next prime is 81898777. The reversal of 81898772 is 27789818.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 43903876 + 37994896 = 6626^2 + 6164^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 81898772.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81898777) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10237343 + ... + 10237350.

It is an arithmetic number, because the mean of its divisors is an integer number (23887143).

Almost surely, 2^81898772 is an apocalyptic number.

It is an amenable number.

81898772 is a deficient number, since it is larger than the sum of its proper divisors (61424086).

81898772 is a wasteful number, since it uses less digits than its factorization.

81898772 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20474697 (or 20474695 counting only the distinct ones).

The product of its digits is 451584, while the sum is 50.

The square root of 81898772 is about 9049.7940308053. The cubic root of 81898772 is about 434.2693013146.

It can be divided in two parts, 8189 and 8772, that added together give a palindrome (16961).

The spelling of 81898772 in words is "eighty-one million, eight hundred ninety-eight thousand, seven hundred seventy-two".