21202011020521 has 2 divisors, whose sum is σ = 21202011020522. Its totient is φ = 21202011020520.

The previous prime is 21202011020483. The next prime is 21202011020537. The reversal of 21202011020521 is 12502011020212.

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., 19637350274025 + 1564660746496 = 4431405^2 + 1250864^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21202011020521 is a prime.

It is a super-2 number, since 2×21202011020521² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21202011020551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10601005510260 + 10601005510261.

It is an arithmetic number, because the mean of its divisors is an integer number (10601005510261).

Almost surely, 2^{21202011020521} is an apocalyptic number.

It is an amenable number.

21202011020521 is a deficient number, since it is larger than the sum of its proper divisors (1).

21202011020521 is an equidigital number, since it uses as much as digits as its factorization.

21202011020521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 160, while the sum is 19.

Adding to 21202011020521 its reverse (12502011020212), we get a palindrome (33704022040733).

The spelling of 21202011020521 in words is "twenty-one trillion, two hundred two billion, eleven million, twenty thousand, five hundred twenty-one".