28400916221001 has 15 divisors (see below), whose sum is σ = 42426131682781. Its totient is φ = 18933912171828.

The previous prime is 28400916220903. The next prime is 28400916221009. The reversal of 28400916221001 is 10012261900482.

The square root of 28400916221001 is 5329251.

It is a perfect power (a square), and thus also a powerful number.

28400916221001 is a `hidden beast` number, since 2 + 8 + 400 + 91 + 62 + 2 + 100 + 1 = 666.

It is not a de Polignac number, because 28400916221001 - 2²³ = 28400907832393 is a prime.

It is a super-2 number, since 2×28400916221001² (a number of 28 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28400916221009) by changing a digit.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 47667190 + ... + 48259328.

Almost surely, 2^{28400916221001} is an apocalyptic number.

28400916221001 is the 5329251-st square number.

28400916221001 is the 2664626-th centered octagonal number.

It is an amenable number.

28400916221001 is a deficient number, since it is larger than the sum of its proper divisors (14025215461780).

28400916221001 is an frugal number, since it uses more digits than its factorization.

28400916221001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1184290 (or 592142 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 36.

The spelling of 28400916221001 in words is "twenty-eight trillion, four hundred billion, nine hundred sixteen million, two hundred twenty-one thousand, one".