405640521 has 48 divisors (see below), whose sum is σ = 711432960. Its totient is φ = 226908000.

The previous prime is 405640513. The next prime is 405640523. The reversal of 405640521 is 125046504.

It is not a de Polignac number, because 405640521 - 2³ = 405640513 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (405640523) 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 in 47 ways as a sum of consecutive naturals, for example, 37696 + ... + 47246.

It is an arithmetic number, because the mean of its divisors is an integer number (14821520).

Almost surely, 2^405640521 is an apocalyptic number.

It is an amenable number.

405640521 is a deficient number, since it is larger than the sum of its proper divisors (305792439).

405640521 is a wasteful number, since it uses less digits than its factorization.

405640521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9595 (or 9578 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 27.

The square root of 405640521 is about 20140.5193825780. The cubic root of 405640521 is about 740.2534565196.

The spelling of 405640521 in words is "four hundred five million, six hundred forty thousand, five hundred twenty-one".