421809917 has 2 divisors, whose sum is σ = 421809918. Its totient is φ = 421809916.

The previous prime is 421809887. The next prime is 421809923. The reversal of 421809917 is 719908124.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 409900516 + 11909401 = 20246^2 + 3451^2 .

It is a cyclic number.

It is not a de Polignac number, because 421809917 - 2¹² = 421805821 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (421809977) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 210904958 + 210904959.

It is an arithmetic number, because the mean of its divisors is an integer number (210904959).

Almost surely, 2^421809917 is an apocalyptic number.

It is an amenable number.

421809917 is a deficient number, since it is larger than the sum of its proper divisors (1).

421809917 is an equidigital number, since it uses as much as digits as its factorization.

421809917 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36288, while the sum is 41.

The square root of 421809917 is about 20538.0115152368. The cubic root of 421809917 is about 749.9614303128.

The spelling of 421809917 in words is "four hundred twenty-one million, eight hundred nine thousand, nine hundred seventeen".