21291967 has 2 divisors, whose sum is σ = 21291968. Its totient is φ = 21291966.

The previous prime is 21291961. The next prime is 21291971. The reversal of 21291967 is 76919212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21291967 - 2⁷ = 21291839 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 (21291961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10645983 + 10645984.

It is an arithmetic number, because the mean of its divisors is an integer number (10645984).

Almost surely, 2^21291967 is an apocalyptic number.

21291967 is a deficient number, since it is larger than the sum of its proper divisors (1).

21291967 is an equidigital number, since it uses as much as digits as its factorization.

21291967 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13608, while the sum is 37.

The square root of 21291967 is about 4614.3219436879. The cubic root of 21291967 is about 277.1651324149.

It can be divided in two parts, 2129 and 1967, that added together give a 12-th power (4096 = 2¹²).

The spelling of 21291967 in words is "twenty-one million, two hundred ninety-one thousand, nine hundred sixty-seven".