21717667 has 2 divisors, whose sum is σ = 21717668. Its totient is φ = 21717666.

The previous prime is 21717649. The next prime is 21717679. The reversal of 21717667 is 76671712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21717667 - 2⁷ = 21717539 is a prime.

It is not a weakly prime, because it can be changed into another prime (21717617) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10858833 + 10858834.

It is an arithmetic number, because the mean of its divisors is an integer number (10858834).

Almost surely, 2^21717667 is an apocalyptic number.

21717667 is a deficient number, since it is larger than the sum of its proper divisors (1).

21717667 is an equidigital number, since it uses as much as digits as its factorization.

21717667 is an evil number, because the sum of its binary digits is even.

The product of its digits is 24696, while the sum is 37.

The square root of 21717667 is about 4660.2217758386. The cubic root of 21717667 is about 279.0001199025. Note that the first 3 decimals are identical.

The spelling of 21717667 in words is "twenty-one million, seven hundred seventeen thousand, six hundred sixty-seven".