21789967 has 2 divisors, whose sum is σ = 21789968. Its totient is φ = 21789966.

The previous prime is 21789919. The next prime is 21789997. The reversal of 21789967 is 76998712.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21789967 - 2⁷ = 21789839 is a prime.

It is a super-2 number, since 2×21789967² = 949605323722178, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21789967.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21789917) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10894983 + 10894984.

It is an arithmetic number, because the mean of its divisors is an integer number (10894984).

Almost surely, 2^21789967 is an apocalyptic number.

21789967 is a deficient number, since it is larger than the sum of its proper divisors (1).

21789967 is an equidigital number, since it uses as much as digits as its factorization.

21789967 is an evil number, because the sum of its binary digits is even.

The product of its digits is 381024, while the sum is 49.

The square root of 21789967 is about 4667.9724720696. The cubic root of 21789967 is about 279.3093821807.

The spelling of 21789967 in words is "twenty-one million, seven hundred eighty-nine thousand, nine hundred sixty-seven".