405445021 has 4 divisors (see below), whose sum is σ = 405530944. Its totient is φ = 405359100.

The previous prime is 405444973. The next prime is 405445031. The reversal of 405445021 is 120544504.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-405445021 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 (405445031) 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, 35445 + ... + 45466.

It is an arithmetic number, because the mean of its divisors is an integer number (101382736).

Almost surely, 2^405445021 is an apocalyptic number.

It is an amenable number.

405445021 is a deficient number, since it is larger than the sum of its proper divisors (85923).

405445021 is an equidigital number, since it uses as much as digits as its factorization.

405445021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85922.

The product of its (nonzero) digits is 3200, while the sum is 25.

The square root of 405445021 is about 20135.6653974980. The cubic root of 405445021 is about 740.1345147482.

Adding to 405445021 its reverse (120544504), we get a palindrome (525989525).

The spelling of 405445021 in words is "four hundred five million, four hundred forty-five thousand, twenty-one".