28197731 has 2 divisors, whose sum is σ = 28197732. Its totient is φ = 28197730.

The previous prime is 28197647. The next prime is 28197733. The reversal of 28197731 is 13779182.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 28197731 - 2¹⁴ = 28181347 is a prime.

It is a super-2 number, since 2×28197731² = 1590224067096722, which contains 22 as substring.

Together with 28197733, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (28197733) 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, 14098865 + 14098866.

It is an arithmetic number, because the mean of its divisors is an integer number (14098866).

Almost surely, 2^28197731 is an apocalyptic number.

28197731 is a deficient number, since it is larger than the sum of its proper divisors (1).

28197731 is an equidigital number, since it uses as much as digits as its factorization.

28197731 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 21168, while the sum is 38.

The square root of 28197731 is about 5310.1535759336. The cubic root of 28197731 is about 304.3720161421.

The spelling of 28197731 in words is "twenty-eight million, one hundred ninety-seven thousand, seven hundred thirty-one".