20445521 has 2 divisors, whose sum is σ = 20445522. Its totient is φ = 20445520.

The previous prime is 20445499. The next prime is 20445533. The reversal of 20445521 is 12554402.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11971600 + 8473921 = 3460^2 + 2911^2 .

It is a cyclic number.

It is not a de Polignac number, because 20445521 - 2¹⁰ = 20444497 is a prime.

It is a super-2 number, since 2×20445521² = 836038657922882, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20445541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10222760 + 10222761.

It is an arithmetic number, because the mean of its divisors is an integer number (10222761).

Almost surely, 2^20445521 is an apocalyptic number.

It is an amenable number.

20445521 is a deficient number, since it is larger than the sum of its proper divisors (1).

20445521 is an equidigital number, since it uses as much as digits as its factorization.

20445521 is an odious number, because the sum of its binary digits is odd.

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

The square root of 20445521 is about 4521.6723676091. The cubic root of 20445521 is about 273.4425280882.

Adding to 20445521 its reverse (12554402), we get a palindrome (32999923).

The spelling of 20445521 in words is "twenty million, four hundred forty-five thousand, five hundred twenty-one".