28977721668 has 72 divisors (see below), whose sum is σ = 83750651712. Its totient is φ = 8275666752.

The previous prime is 28977721657. The next prime is 28977721673. The reversal of 28977721668 is 86612777982.

It is a hoax number, since the sum of its digits (63) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 569571 + ... + 618357.

It is an arithmetic number, because the mean of its divisors is an integer number (1163203496).

Almost surely, 2^28977721668 is an apocalyptic number.

28977721668 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

28977721668 is an abundant number, since it is smaller than the sum of its proper divisors (54772930044).

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

28977721668 is a wasteful number, since it uses less digits than its factorization.

28977721668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51161 (or 51156 counting only the distinct ones).

The product of its digits is 28449792, while the sum is 63.

The spelling of 28977721668 in words is "twenty-eight billion, nine hundred seventy-seven million, seven hundred twenty-one thousand, six hundred sixty-eight".