28177991 has 2 divisors, whose sum is σ = 28177992. Its totient is φ = 28177990.

The previous prime is 28177949. The next prime is 28177997. The reversal of 28177991 is 19977182.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28177991 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28177997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14088995 + 14088996.

It is an arithmetic number, because the mean of its divisors is an integer number (14088996).

Almost surely, 2^28177991 is an apocalyptic number.

28177991 is a deficient number, since it is larger than the sum of its proper divisors (1).

28177991 is an equidigital number, since it uses as much as digits as its factorization.

28177991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 63504, while the sum is 44.

The square root of 28177991 is about 5308.2945472157. The cubic root of 28177991 is about 304.3009737097.

The spelling of 28177991 in words is "twenty-eight million, one hundred seventy-seven thousand, nine hundred ninety-one".