28553781 has 16 divisors (see below), whose sum is σ = 38750400. Its totient is φ = 18699648.

The previous prime is 28553779. The next prime is 28553809. The reversal of 28553781 is 18735582.

It is not a de Polignac number, because 28553781 - 2¹ = 28553779 is a prime.

It is a super-2 number, since 2×28553781² = 1630636818791922, which 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 (28553881) 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, 60910 + ... + 61376.

It is an arithmetic number, because the mean of its divisors is an integer number (2421900).

Almost surely, 2^28553781 is an apocalyptic number.

It is an amenable number.

28553781 is a deficient number, since it is larger than the sum of its proper divisors (10196619).

28553781 is a wasteful number, since it uses less digits than its factorization.

28553781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 788.

The product of its digits is 67200, while the sum is 39.

The square root of 28553781 is about 5343.5738041127. The cubic root of 28553781 is about 305.6477535010.

The spelling of 28553781 in words is "twenty-eight million, five hundred fifty-three thousand, seven hundred eighty-one".