21366805649 has 8 divisors (see below), whose sum is σ = 24783672768. Its totient is φ = 18041055120.

The previous prime is 21366805639. The next prime is 21366805667. The reversal of 21366805649 is 94650866312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21366805649 - 2²⁰ = 21365757073 is a prime.

It is a super-2 number, since 2×21366805649² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21366805597 and 21366805606.

It is not an unprimeable number, because it can be changed into a prime (21366805609) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22778642 + ... + 22779579.

It is an arithmetic number, because the mean of its divisors is an integer number (3097959096).

Almost surely, 2^21366805649 is an apocalyptic number.

It is an amenable number.

21366805649 is a deficient number, since it is larger than the sum of its proper divisors (3416867119).

21366805649 is an equidigital number, since it uses as much as digits as its factorization.

21366805649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45558295.

The product of its (nonzero) digits is 1866240, while the sum is 50.

The spelling of 21366805649 in words is "twenty-one billion, three hundred sixty-six million, eight hundred five thousand, six hundred forty-nine".