21002202421 has 2 divisors, whose sum is σ = 21002202422. Its totient is φ = 21002202420.

The previous prime is 21002202379. The next prime is 21002202439. The reversal of 21002202421 is 12420220012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18472615396 + 2529587025 = 135914^2 + 50295^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21002202421 is a prime.

It is a super-2 number, since 2×21002202421² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21002202395 and 21002202404.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21002202521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10501101210 + 10501101211.

It is an arithmetic number, because the mean of its divisors is an integer number (10501101211).

Almost surely, 2^21002202421 is an apocalyptic number.

It is an amenable number.

21002202421 is a deficient number, since it is larger than the sum of its proper divisors (1).

21002202421 is an equidigital number, since it uses as much as digits as its factorization.

21002202421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 128, while the sum is 16.

Adding to 21002202421 its reverse (12420220012), we get a palindrome (33422422433).

The spelling of 21002202421 in words is "twenty-one billion, two million, two hundred two thousand, four hundred twenty-one".