405706621 has 4 divisors (see below), whose sum is σ = 405982044. Its totient is φ = 405431200.

The previous prime is 405706577. The next prime is 405706643. The reversal of 405706621 is 126607504.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 303979225 + 101727396 = 17435^2 + 10086^2 .

It is a cyclic number.

It is not a de Polignac number, because 405706621 - 2⁷ = 405706493 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (405706121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 135490 + ... + 138451.

It is an arithmetic number, because the mean of its divisors is an integer number (101495511).

Almost surely, 2^405706621 is an apocalyptic number.

It is an amenable number.

405706621 is a deficient number, since it is larger than the sum of its proper divisors (275423).

405706621 is a wasteful number, since it uses less digits than its factorization.

405706621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 275422.

The product of its (nonzero) digits is 10080, while the sum is 31.

The square root of 405706621 is about 20142.1602863248. The cubic root of 405706621 is about 740.2936629696.

The spelling of 405706621 in words is "four hundred five million, seven hundred six thousand, six hundred twenty-one".