28139957 has 2 divisors, whose sum is σ = 28139958. Its totient is φ = 28139956.

The previous prime is 28139941. The next prime is 28139963. The reversal of 28139957 is 75993182.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 26306641 + 1833316 = 5129^2 + 1354^2 .

It is a cyclic number.

It is not a de Polignac number, because 28139957 - 2⁴ = 28139941 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28139977) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14069978 + 14069979.

It is an arithmetic number, because the mean of its divisors is an integer number (14069979).

Almost surely, 2^28139957 is an apocalyptic number.

It is an amenable number.

28139957 is a deficient number, since it is larger than the sum of its proper divisors (1).

28139957 is an equidigital number, since it uses as much as digits as its factorization.

28139957 is an evil number, because the sum of its binary digits is even.

The product of its digits is 136080, while the sum is 44.

The square root of 28139957 is about 5304.7108309502. The cubic root of 28139957 is about 304.1639992594.

The spelling of 28139957 in words is "twenty-eight million, one hundred thirty-nine thousand, nine hundred fifty-seven".