21261011656631 has 2 divisors, whose sum is σ = 21261011656632. Its totient is φ = 21261011656630.

The previous prime is 21261011656603. The next prime is 21261011656637. The reversal of 21261011656631 is 13665611016212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21261011656631 - 2⁶ = 21261011656567 is a prime.

It is a super-2 number, since 2×21261011656631² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21261011656637) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10630505828315 + 10630505828316.

It is an arithmetic number, because the mean of its divisors is an integer number (10630505828316).

Almost surely, 2^{21261011656631} is an apocalyptic number.

21261011656631 is a deficient number, since it is larger than the sum of its proper divisors (1).

21261011656631 is an equidigital number, since it uses as much as digits as its factorization.

21261011656631 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 77760, while the sum is 41.

The spelling of 21261011656631 in words is "twenty-one trillion, two hundred sixty-one billion, eleven million, six hundred fifty-six thousand, six hundred thirty-one".