21002121010061 has 2 divisors, whose sum is σ = 21002121010062. Its totient is φ = 21002121010060.

The previous prime is 21002121010049. The next prime is 21002121010153. The reversal of 21002121010061 is 16001012120012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11359636604836 + 9642484405225 = 3370406^2 + 3105235^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21002121010061 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21002121010561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10501060505030 + 10501060505031.

It is an arithmetic number, because the mean of its divisors is an integer number (10501060505031).

Almost surely, 2^{21002121010061} is an apocalyptic number.

It is an amenable number.

21002121010061 is a deficient number, since it is larger than the sum of its proper divisors (1).

21002121010061 is an equidigital number, since it uses as much as digits as its factorization.

21002121010061 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 48, while the sum is 17.

Adding to 21002121010061 its reverse (16001012120012), we get a palindrome (37003133130073).

The spelling of 21002121010061 in words is "twenty-one trillion, two billion, one hundred twenty-one million, ten thousand, sixty-one".