20137206521 has 2 divisors, whose sum is σ = 20137206522. Its totient is φ = 20137206520.

The previous prime is 20137206421. The next prime is 20137206527. The reversal of 20137206521 is 12560273102.

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., 10584294400 + 9552912121 = 102880^2 + 97739^2 .

It is a cyclic number.

It is not a de Polignac number, because 20137206521 - 2¹⁴ = 20137190137 is a prime.

It is not a weakly prime, because it can be changed into another prime (20137206527) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10068603260 + 10068603261.

It is an arithmetic number, because the mean of its divisors is an integer number (10068603261).

Almost surely, 2^20137206521 is an apocalyptic number.

It is an amenable number.

20137206521 is a deficient number, since it is larger than the sum of its proper divisors (1).

20137206521 is an equidigital number, since it uses as much as digits as its factorization.

20137206521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5040, while the sum is 29.

Adding to 20137206521 its reverse (12560273102), we get a palindrome (32697479623).

The spelling of 20137206521 in words is "twenty billion, one hundred thirty-seven million, two hundred six thousand, five hundred twenty-one".