21099667 has 2 divisors, whose sum is σ = 21099668. Its totient is φ = 21099666.

The previous prime is 21099649. The next prime is 21099677. The reversal of 21099667 is 76699012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21099667 - 2⁷ = 21099539 is a prime.

It is not a weakly prime, because it can be changed into another prime (21099677) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10549833 + 10549834.

It is an arithmetic number, because the mean of its divisors is an integer number (10549834).

Almost surely, 2^21099667 is an apocalyptic number.

21099667 is a deficient number, since it is larger than the sum of its proper divisors (1).

21099667 is an equidigital number, since it uses as much as digits as its factorization.

21099667 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 40824, while the sum is 40.

The square root of 21099667 is about 4593.4373839207. The cubic root of 21099667 is about 276.3281951405.

The spelling of 21099667 in words is "twenty-one million, ninety-nine thousand, six hundred sixty-seven".