8721157 has 2 divisors, whose sum is σ = 8721158. Its totient is φ = 8721156.

The previous prime is 8721121. The next prime is 8721191. The reversal of 8721157 is 7511278.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6548481 + 2172676 = 2559^2 + 1474^2 .

It is a cyclic number.

It is not a de Polignac number, because 8721157 - 2⁷ = 8721029 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8721197) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4360578 + 4360579.

It is an arithmetic number, because the mean of its divisors is an integer number (4360579).

Almost surely, 2^8721157 is an apocalyptic number.

It is an amenable number.

8721157 is a deficient number, since it is larger than the sum of its proper divisors (1).

8721157 is an equidigital number, since it uses as much as digits as its factorization.

8721157 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3920, while the sum is 31.

The square root of 8721157 is about 2953.1605103685. The cubic root of 8721157 is about 205.8375962591.

The spelling of 8721157 in words is "eight million, seven hundred twenty-one thousand, one hundred fifty-seven".