28557731 has 2 divisors, whose sum is σ = 28557732. Its totient is φ = 28557730.

The previous prime is 28557707. The next prime is 28557757. The reversal of 28557731 is 13775582.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 28557731 - 2⁶ = 28557667 is a prime.

It is a super-2 number, since 2×28557731² = 1631087999736722, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (28557701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14278865 + 14278866.

It is an arithmetic number, because the mean of its divisors is an integer number (14278866).

Almost surely, 2^28557731 is an apocalyptic number.

28557731 is a deficient number, since it is larger than the sum of its proper divisors (1).

28557731 is an equidigital number, since it uses as much as digits as its factorization.

28557731 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 58800, while the sum is 38.

The square root of 28557731 is about 5343.9433941613. The cubic root of 28557731 is about 305.6618468239.

The spelling of 28557731 in words is "twenty-eight million, five hundred fifty-seven thousand, seven hundred thirty-one".