21609960649 has 2 divisors, whose sum is σ = 21609960650. Its totient is φ = 21609960648.

The previous prime is 21609960611. The next prime is 21609960689. The reversal of 21609960649 is 94606990612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20724481600 + 885479049 = 143960^2 + 29757^2 .

It is a cyclic number.

It is not a de Polignac number, because 21609960649 - 2⁷ = 21609960521 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21609960596 and 21609960605.

It is not a weakly prime, because it can be changed into another prime (21609960689) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10804980324 + 10804980325.

It is an arithmetic number, because the mean of its divisors is an integer number (10804980325).

Almost surely, 2^21609960649 is an apocalyptic number.

It is an amenable number.

21609960649 is a deficient number, since it is larger than the sum of its proper divisors (1).

21609960649 is an equidigital number, since it uses as much as digits as its factorization.

21609960649 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1259712, while the sum is 52.

The spelling of 21609960649 in words is "twenty-one billion, six hundred nine million, nine hundred sixty thousand, six hundred forty-nine".