21642884449 has 2 divisors, whose sum is σ = 21642884450. Its totient is φ = 21642884448.

The previous prime is 21642884423. The next prime is 21642884479. The reversal of 21642884449 is 94448824612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15219663424 + 6423221025 = 123368^2 + 80145^2 .

It is a cyclic number.

It is not a de Polignac number, because 21642884449 - 2¹³ = 21642876257 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21642884396 and 21642884405.

It is not a weakly prime, because it can be changed into another prime (21642884479) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10821442224 + 10821442225.

It is an arithmetic number, because the mean of its divisors is an integer number (10821442225).

Almost surely, 2^21642884449 is an apocalyptic number.

It is an amenable number.

21642884449 is a deficient number, since it is larger than the sum of its proper divisors (1).

21642884449 is an equidigital number, since it uses as much as digits as its factorization.

21642884449 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3538944, while the sum is 52.

The spelling of 21642884449 in words is "twenty-one billion, six hundred forty-two million, eight hundred eighty-four thousand, four hundred forty-nine".