21261011656603 has 2 divisors, whose sum is σ = 21261011656604. Its totient is φ = 21261011656602.

The previous prime is 21261011656589. The next prime is 21261011656631. The reversal of 21261011656603 is 30665611016212.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21261011656603 - 2⁵ = 21261011656571 is a prime.

It is not a weakly prime, because it can be changed into another prime (21261011656903) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10630505828301 + 10630505828302.

It is an arithmetic number, because the mean of its divisors is an integer number (10630505828302).

Almost surely, 2^{21261011656603} is an apocalyptic number.

21261011656603 is a deficient number, since it is larger than the sum of its proper divisors (1).

21261011656603 is an equidigital number, since it uses as much as digits as its factorization.

21261011656603 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 77760, while the sum is 40.

The spelling of 21261011656603 in words is "twenty-one trillion, two hundred sixty-one billion, eleven million, six hundred fifty-six thousand, six hundred three".