21665502007 has 2 divisors, whose sum is σ = 21665502008. Its totient is φ = 21665502006.

The previous prime is 21665501999. The next prime is 21665502017. The reversal of 21665502007 is 70020556612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21665502007 - 2³ = 21665501999 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21665502017) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10832751003 + 10832751004.

It is an arithmetic number, because the mean of its divisors is an integer number (10832751004).

Almost surely, 2^21665502007 is an apocalyptic number.

21665502007 is a deficient number, since it is larger than the sum of its proper divisors (1).

21665502007 is an equidigital number, since it uses as much as digits as its factorization.

21665502007 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 25200, while the sum is 34.

The spelling of 21665502007 in words is "twenty-one billion, six hundred sixty-five million, five hundred two thousand, seven".