28440654921 has 18 divisors (see below), whose sum is σ = 47788039962. Its totient is φ = 16251802560.

The previous prime is 28440654863. The next prime is 28440654947. The reversal of 28440654921 is 12945604482.

It is a happy number.

28440654921 is a `hidden beast` number, since 2 + 84 + 4 + 0 + 6 + 549 + 21 = 666.

It can be written as a sum of positive squares in only one way, i.e., 26720479296 + 1720175625 = 163464^2 + 41475^2 .

It is not a de Polignac number, because 28440654921 - 2⁷ = 28440654793 is a prime.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (28440654961) by changing a digit.

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 17 ways as a sum of consecutive naturals, for example, 32245200 + ... + 32246081.

It is an arithmetic number, because the mean of its divisors is an integer number (2654891109).

Almost surely, 2^28440654921 is an apocalyptic number.

28440654921 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

28440654921 is a deficient number, since it is larger than the sum of its proper divisors (19347385041).

28440654921 is a wasteful number, since it uses less digits than its factorization.

28440654921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64491301 (or 64491291 counting only the distinct ones).

The product of its (nonzero) digits is 552960, while the sum is 45.

The spelling of 28440654921 in words is "twenty-eight billion, four hundred forty million, six hundred fifty-four thousand, nine hundred twenty-one".