20357521 has 2 divisors, whose sum is σ = 20357522. Its totient is φ = 20357520.

The previous prime is 20357509. The next prime is 20357527. The reversal of 20357521 is 12575302.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19009600 + 1347921 = 4360^2 + 1161^2 .

It is a cyclic number.

It is not a de Polignac number, because 20357521 - 2⁵ = 20357489 is a prime.

It is a super-2 number, since 2×20357521² = 828857322530882, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20357527) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10178760 + 10178761.

It is an arithmetic number, because the mean of its divisors is an integer number (10178761).

Almost surely, 2^20357521 is an apocalyptic number.

It is an amenable number.

20357521 is a deficient number, since it is larger than the sum of its proper divisors (1).

20357521 is an equidigital number, since it uses as much as digits as its factorization.

20357521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2100, while the sum is 25.

The square root of 20357521 is about 4511.9309613512. The cubic root of 20357521 is about 273.0496539630.

The spelling of 20357521 in words is "twenty million, three hundred fifty-seven thousand, five hundred twenty-one".