28491288981 has 16 divisors (see below), whose sum is σ = 38283708288. Its totient is φ = 18846662400.

The previous prime is 28491288979. The next prime is 28491289019. The reversal of 28491288981 is 18988219482.

It is not a de Polignac number, because 28491288981 - 2¹ = 28491288979 is a prime.

It is a super-2 number, since 2×28491288981² (a number of 22 digits) contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28491288181) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 922296 + ... + 952686.

It is an arithmetic number, because the mean of its divisors is an integer number (2392731768).

Almost surely, 2^28491288981 is an apocalyptic number.

It is an amenable number.

28491288981 is a deficient number, since it is larger than the sum of its proper divisors (9792419307).

28491288981 is a wasteful number, since it uses less digits than its factorization.

28491288981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32812.

The product of its digits is 5308416, while the sum is 60.

The spelling of 28491288981 in words is "twenty-eight billion, four hundred ninety-one million, two hundred eighty-eight thousand, nine hundred eighty-one".