21918607 has 2 divisors, whose sum is σ = 21918608. Its totient is φ = 21918606.

The previous prime is 21918601. The next prime is 21918649. The reversal of 21918607 is 70681912.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21918607 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21918601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10959303 + 10959304.

It is an arithmetic number, because the mean of its divisors is an integer number (10959304).

Almost surely, 2^21918607 is an apocalyptic number.

21918607 is a deficient number, since it is larger than the sum of its proper divisors (1).

21918607 is an equidigital number, since it uses as much as digits as its factorization.

21918607 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6048, while the sum is 34.

The square root of 21918607 is about 4681.7311968971. The cubic root of 21918607 is about 279.8579509073.

The spelling of 21918607 in words is "twenty-one million, nine hundred eighteen thousand, six hundred seven".