21646807001 has 2 divisors, whose sum is σ = 21646807002. Its totient is φ = 21646807000.

The previous prime is 21646806977. The next prime is 21646807003. The reversal of 21646807001 is 10070864612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21584017225 + 62789776 = 146915^2 + 7924^2 .

It is a cyclic number.

It is not a de Polignac number, because 21646807001 - 2¹⁰ = 21646805977 is a prime.

It is a super-2 number, since 2×21646807001² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

Together with 21646807003, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21646807003) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10823403500 + 10823403501.

It is an arithmetic number, because the mean of its divisors is an integer number (10823403501).

Almost surely, 2^21646807001 is an apocalyptic number.

It is an amenable number.

21646807001 is a deficient number, since it is larger than the sum of its proper divisors (1).

21646807001 is an equidigital number, since it uses as much as digits as its factorization.

21646807001 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16128, while the sum is 35.

The spelling of 21646807001 in words is "twenty-one billion, six hundred forty-six million, eight hundred seven thousand, one".