21156241 has 2 divisors, whose sum is σ = 21156242. Its totient is φ = 21156240.

The previous prime is 21156227. The next prime is 21156257. The reversal of 21156241 is 14265112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19989841 + 1166400 = 4471^2 + 1080^2 .

It is a cyclic number.

It is not a de Polignac number, because 21156241 - 2¹¹ = 21154193 is a prime.

It is equal to p_1339213 and since 21156241 and 1339213 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (21156271) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10578120 + 10578121.

It is an arithmetic number, because the mean of its divisors is an integer number (10578121).

Almost surely, 2^21156241 is an apocalyptic number.

It is an amenable number.

21156241 is a deficient number, since it is larger than the sum of its proper divisors (1).

21156241 is an equidigital number, since it uses as much as digits as its factorization.

21156241 is an evil number, because the sum of its binary digits is even.

The product of its digits is 480, while the sum is 22.

The square root of 21156241 is about 4599.5913948959. The cubic root of 21156241 is about 276.5749453218.

The spelling of 21156241 in words is "twenty-one million, one hundred fifty-six thousand, two hundred forty-one".