40208521 has 4 divisors (see below), whose sum is σ = 40221252. Its totient is φ = 40195792.

The previous prime is 40208491. The next prime is 40208527. The reversal of 40208521 is 12580204.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 26988025 + 13220496 = 5195^2 + 3636^2 .

It is a cyclic number.

It is not a de Polignac number, because 40208521 - 2¹⁵ = 40175753 is a prime.

It is a super-2 number, since 2×40208521² = 3233450322014882, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 40208492 and 40208501.

It is not an unprimeable number, because it can be changed into a prime (40208527) 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, 2355 + ... + 9271.

It is an arithmetic number, because the mean of its divisors is an integer number (10055313).

Almost surely, 2^40208521 is an apocalyptic number.

It is an amenable number.

40208521 is a deficient number, since it is larger than the sum of its proper divisors (12731).

40208521 is an equidigital number, since it uses as much as digits as its factorization.

40208521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12730.

The product of its (nonzero) digits is 640, while the sum is 22.

The square root of 40208521 is about 6341.0189244316. The cubic root of 40208521 is about 342.5884361469.

Adding to 40208521 its reverse (12580204), we get a palindrome (52788725).

The spelling of 40208521 in words is "forty million, two hundred eight thousand, five hundred twenty-one".