21612634630661 has 2 divisors, whose sum is σ = 21612634630662. Its totient is φ = 21612634630660.

The previous prime is 21612634630651. The next prime is 21612634630663. The reversal of 21612634630661 is 16603643621612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21524496302500 + 88138328161 = 4639450^2 + 296881^2 .

It is a cyclic number.

It is not a de Polignac number, because 21612634630661 - 2⁶ = 21612634630597 is a prime.

Together with 21612634630663, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21612634630663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10806317315330 + 10806317315331.

It is an arithmetic number, because the mean of its divisors is an integer number (10806317315331).

Almost surely, 2^{21612634630661} is an apocalyptic number.

It is an amenable number.

21612634630661 is a deficient number, since it is larger than the sum of its proper divisors (1).

21612634630661 is an equidigital number, since it uses as much as digits as its factorization.

21612634630661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1119744, while the sum is 47.

The spelling of 21612634630661 in words is "twenty-one trillion, six hundred twelve billion, six hundred thirty-four million, six hundred thirty thousand, six hundred sixty-one".