21167257 has 2 divisors, whose sum is σ = 21167258. Its totient is φ = 21167256.

The previous prime is 21167239. The next prime is 21167297. The reversal of 21167257 is 75276112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13220496 + 7946761 = 3636^2 + 2819^2 .

It is a cyclic number.

It is not a de Polignac number, because 21167257 - 2¹⁵ = 21134489 is a prime.

It is not a weakly prime, because it can be changed into another prime (21167297) 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, 10583628 + 10583629.

It is an arithmetic number, because the mean of its divisors is an integer number (10583629).

Almost surely, 2^21167257 is an apocalyptic number.

It is an amenable number.

21167257 is a deficient number, since it is larger than the sum of its proper divisors (1).

21167257 is an equidigital number, since it uses as much as digits as its factorization.

21167257 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5880, while the sum is 31.

The square root of 21167257 is about 4600.7887367276. The cubic root of 21167257 is about 276.6229409454.

The spelling of 21167257 in words is "twenty-one million, one hundred sixty-seven thousand, two hundred fifty-seven".