405109921 has 2 divisors, whose sum is σ = 405109922. Its totient is φ = 405109920.

The previous prime is 405109919. The next prime is 405109951. The reversal of 405109921 is 129901504.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 377136400 + 27973521 = 19420^2 + 5289^2 .

It is a cyclic number.

It is not a de Polignac number, because 405109921 - 2¹ = 405109919 is a prime.

It is a super-2 number, since 2×405109921² = 328228096185252482, which contains 22 as substring.

Together with 405109919, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (405109951) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 202554960 + 202554961.

It is an arithmetic number, because the mean of its divisors is an integer number (202554961).

Almost surely, 2^405109921 is an apocalyptic number.

It is an amenable number.

405109921 is a deficient number, since it is larger than the sum of its proper divisors (1).

405109921 is an equidigital number, since it uses as much as digits as its factorization.

405109921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3240, while the sum is 31.

The square root of 405109921 is about 20127.3426214193. The cubic root of 405109921 is about 739.9305516759.

The spelling of 405109921 in words is "four hundred five million, one hundred nine thousand, nine hundred twenty-one".