28040251 has 4 divisors (see below), whose sum is σ = 28355400. Its totient is φ = 27725104.

The previous prime is 28040239. The next prime is 28040261. The reversal of 28040251 is 15204082.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28040251 is a prime.

It is a super-2 number, since 2×28040251² = 1572511352286002, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (28040231) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 157441 + ... + 157618.

It is an arithmetic number, because the mean of its divisors is an integer number (7088850).

Almost surely, 2^28040251 is an apocalyptic number.

28040251 is a deficient number, since it is larger than the sum of its proper divisors (315149).

28040251 is an equidigital number, since it uses as much as digits as its factorization.

28040251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 315148.

The product of its (nonzero) digits is 640, while the sum is 22.

The square root of 28040251 is about 5295.3046182444. The cubic root of 28040251 is about 303.8043343560.

The spelling of 28040251 in words is "twenty-eight million, forty thousand, two hundred fifty-one".