21000012100621 has 2 divisors, whose sum is σ = 21000012100622. Its totient is φ = 21000012100620.

The previous prime is 21000012100591. The next prime is 21000012100679. The reversal of 21000012100621 is 12600121000012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20862841867396 + 137170233225 = 4567586^2 + 370365^2 .

It is a cyclic number.

It is not a de Polignac number, because 21000012100621 - 2⁷ = 21000012100493 is a prime.

It is a super-3 number, since 3×21000012100621³ (a number of 41 digits) contains 333 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21000012100595 and 21000012100604.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21000012103621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500006050310 + 10500006050311.

It is an arithmetic number, because the mean of its divisors is an integer number (10500006050311).

Almost surely, 2^{21000012100621} is an apocalyptic number.

It is an amenable number.

21000012100621 is a deficient number, since it is larger than the sum of its proper divisors (1).

21000012100621 is an equidigital number, since it uses as much as digits as its factorization.

21000012100621 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 16.

Adding to 21000012100621 its reverse (12600121000012), we get a palindrome (33600133100633).

The spelling of 21000012100621 in words is "twenty-one trillion, twelve million, one hundred thousand, six hundred twenty-one".