406643621 has 4 divisors (see below), whose sum is σ = 430563852. Its totient is φ = 382723392.

The previous prime is 406643609. The next prime is 406643623. The reversal of 406643621 is 126346604.

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 253255396 + 153388225 = 15914^2 + 12385^2 .

It is a cyclic number.

It is not a de Polignac number, because 406643621 - 2⁶ = 406643557 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (406643623) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11960090 + ... + 11960123.

It is an arithmetic number, because the mean of its divisors is an integer number (107640963).

Almost surely, 2^406643621 is an apocalyptic number.

It is an amenable number.

406643621 is a deficient number, since it is larger than the sum of its proper divisors (23920231).

406643621 is a wasteful number, since it uses less digits than its factorization.

406643621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23920230.

The product of its (nonzero) digits is 20736, while the sum is 32.

The square root of 406643621 is about 20165.4065418974. The cubic root of 406643621 is about 740.8631400251.

The spelling of 406643621 in words is "four hundred six million, six hundred forty-three thousand, six hundred twenty-one".