20521445 has 12 divisors (see below), whose sum is σ = 28646604. Its totient is φ = 14071680.

The previous prime is 20521429. The next prime is 20521447. The reversal of 20521445 is 54412502.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 6964321 + 13557124 = 2639^2 + 3682^2 .

It is not a de Polignac number, because 20521445 - 2⁴ = 20521429 is a prime.

It is a super-2 number, since 2×20521445² = 842259409776050, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 20521445.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20521447) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 41636 + ... + 42125.

It is an arithmetic number, because the mean of its divisors is an integer number (2387217).

Almost surely, 2^20521445 is an apocalyptic number.

It is an amenable number.

20521445 is a deficient number, since it is larger than the sum of its proper divisors (8125159).

20521445 is an equidigital number, since it uses as much as digits as its factorization.

20521445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 83780 (or 83773 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 23.

The square root of 20521445 is about 4530.0601541260. The cubic root of 20521445 is about 273.7805842826.

Adding to 20521445 its reverse (54412502), we get a palindrome (74933947).

The spelling of 20521445 in words is "twenty million, five hundred twenty-one thousand, four hundred forty-five".