21711019961 has 2 divisors, whose sum is σ = 21711019962. Its totient is φ = 21711019960.

The previous prime is 21711019943. The next prime is 21711020017. The reversal of 21711019961 is 16991011712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21710254336 + 765625 = 147344^2 + 875^2 .

It is a cyclic number.

It is not a de Polignac number, because 21711019961 - 2¹⁴ = 21711003577 is a prime.

It is not a weakly prime, because it can be changed into another prime (21711019261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10855509980 + 10855509981.

It is an arithmetic number, because the mean of its divisors is an integer number (10855509981).

Almost surely, 2^21711019961 is an apocalyptic number.

It is an amenable number.

21711019961 is a deficient number, since it is larger than the sum of its proper divisors (1).

21711019961 is an equidigital number, since it uses as much as digits as its factorization.

21711019961 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6804, while the sum is 38.

The spelling of 21711019961 in words is "twenty-one billion, seven hundred eleven million, nineteen thousand, nine hundred sixty-one".