405256021 has 8 divisors (see below), whose sum is σ = 423129024. Its totient is φ = 387404160.

The previous prime is 405255971. The next prime is 405256031. The reversal of 405256021 is 120652504.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 405256021 - 2¹⁵ = 405223253 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 (405256031) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 43630 + ... + 52096.

It is an arithmetic number, because the mean of its divisors is an integer number (52891128).

Almost surely, 2^405256021 is an apocalyptic number.

It is an amenable number.

405256021 is a deficient number, since it is larger than the sum of its proper divisors (17873003).

405256021 is a wasteful number, since it uses less digits than its factorization.

405256021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10571.

The product of its (nonzero) digits is 2400, while the sum is 25.

The square root of 405256021 is about 20130.9716854403. The cubic root of 405256021 is about 740.0194912081.

The spelling of 405256021 in words is "four hundred five million, two hundred fifty-six thousand, twenty-one".