421940509 has 2 divisors, whose sum is σ = 421940510. Its totient is φ = 421940508.

The previous prime is 421940443. The next prime is 421940539. The reversal of 421940509 is 905049124.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 237252409 + 184688100 = 15403^2 + 13590^2 .

It is a cyclic number.

It is not a de Polignac number, because 421940509 - 2¹³ = 421932317 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (421940539) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 210970254 + 210970255.

It is an arithmetic number, because the mean of its divisors is an integer number (210970255).

Almost surely, 2^421940509 is an apocalyptic number.

It is an amenable number.

421940509 is a deficient number, since it is larger than the sum of its proper divisors (1).

421940509 is an equidigital number, since it uses as much as digits as its factorization.

421940509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12960, while the sum is 34.

The square root of 421940509 is about 20541.1905448540. The cubic root of 421940509 is about 750.0388181390.

The spelling of 421940509 in words is "four hundred twenty-one million, nine hundred forty thousand, five hundred nine".