28921299561 has 80 divisors (see below), whose sum is σ = 56206199808. Its totient is φ = 14370760800.

The previous prime is 28921299527. The next prime is 28921299569. The reversal of 28921299561 is 16599212982.

28921299561 is a `hidden beast` number, since 289 + 21 + 299 + 56 + 1 = 666.

It is not a de Polignac number, because 28921299561 - 2¹¹ = 28921297513 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 28921299498 and 28921299507.

It is not an unprimeable number, because it can be changed into a prime (28921299569) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 42646 + ... + 244256.

Almost surely, 2^28921299561 is an apocalyptic number.

28921299561 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

28921299561 is a deficient number, since it is larger than the sum of its proper divisors (27284900247).

28921299561 is a wasteful number, since it uses less digits than its factorization.

28921299561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 201664 (or 201655 counting only the distinct ones).

The product of its digits is 1399680, while the sum is 54.

The spelling of 28921299561 in words is "twenty-eight billion, nine hundred twenty-one million, two hundred ninety-nine thousand, five hundred sixty-one".