21211867 has 2 divisors, whose sum is σ = 21211868. Its totient is φ = 21211866.

The previous prime is 21211859. The next prime is 21211873. The reversal of 21211867 is 76811212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21211867 - 2³ = 21211859 is a prime.

It is not a weakly prime, because it can be changed into another prime (21211807) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605933 + 10605934.

It is an arithmetic number, because the mean of its divisors is an integer number (10605934).

Almost surely, 2^21211867 is an apocalyptic number.

21211867 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211867 is an equidigital number, since it uses as much as digits as its factorization.

21211867 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1344, while the sum is 28.

The square root of 21211867 is about 4605.6342668519. The cubic root of 21211867 is about 276.8171322314.

The spelling of 21211867 in words is "twenty-one million, two hundred eleven thousand, eight hundred sixty-seven".