201520021 has 2 divisors, whose sum is σ = 201520022. Its totient is φ = 201520020.

The previous prime is 201520003. The next prime is 201520031. The reversal of 201520021 is 120025102.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 164480625 + 37039396 = 12825^2 + 6086^2 .

It is a cyclic number.

It is not a de Polignac number, because 201520021 - 2⁷ = 201519893 is a prime.

It is a super-2 number, since 2×201520021² = 81220637727680882, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 201519983 and 201520010.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (201520001) 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, 100760010 + 100760011.

It is an arithmetic number, because the mean of its divisors is an integer number (100760011).

Almost surely, 2^201520021 is an apocalyptic number.

It is an amenable number.

201520021 is a deficient number, since it is larger than the sum of its proper divisors (1).

201520021 is an equidigital number, since it uses as much as digits as its factorization.

201520021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 40, while the sum is 13.

The square root of 201520021 is about 14195.7747587090. The cubic root of 201520021 is about 586.2813329559.

Adding to 201520021 its reverse (120025102), we get a palindrome (321545123).

The spelling of 201520021 in words is "two hundred one million, five hundred twenty thousand, twenty-one".