20165521 has 2 divisors, whose sum is σ = 20165522. Its totient is φ = 20165520.

The previous prime is 20165507. The next prime is 20165533. The reversal of 20165521 is 12556102.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20151121 + 14400 = 4489^2 + 120^2 .

It is a cyclic number.

It is not a de Polignac number, because 20165521 - 2⁵ = 20165489 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20165492 and 20165501.

It is not a weakly prime, because it can be changed into another prime (20165501) 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 as a sum of consecutive naturals, namely, 10082760 + 10082761.

It is an arithmetic number, because the mean of its divisors is an integer number (10082761).

Almost surely, 2^20165521 is an apocalyptic number.

It is an amenable number.

20165521 is a deficient number, since it is larger than the sum of its proper divisors (1).

20165521 is an equidigital number, since it uses as much as digits as its factorization.

20165521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 600, while the sum is 22.

The square root of 20165521 is about 4490.6036342568. The cubic root of 20165521 is about 272.1885272068.

The spelling of 20165521 in words is "twenty million, one hundred sixty-five thousand, five hundred twenty-one".