28321831 has 2 divisors, whose sum is σ = 28321832. Its totient is φ = 28321830.

The previous prime is 28321819. The next prime is 28321861. The reversal of 28321831 is 13812382.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 28321831 - 2⁷ = 28321703 is a prime.

It is a super-2 number, since 2×28321831² = 1604252222385122, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 28321831.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28321801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14160915 + 14160916.

It is an arithmetic number, because the mean of its divisors is an integer number (14160916).

Almost surely, 2^28321831 is an apocalyptic number.

28321831 is a deficient number, since it is larger than the sum of its proper divisors (1).

28321831 is an equidigital number, since it uses as much as digits as its factorization.

28321831 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2304, while the sum is 28.

The square root of 28321831 is about 5321.8259084641. The cubic root of 28321831 is about 304.8178828578.

The spelling of 28321831 in words is "twenty-eight million, three hundred twenty-one thousand, eight hundred thirty-one".