21965366646 has 80 divisors (see below), whose sum is σ = 50778693504. Its totient is φ = 7091525376.

The previous prime is 21965366641. The next prime is 21965366747. The reversal of 21965366646 is 64666356912.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21965366592 and 21965366601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21965366641) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 1328446 + ... + 1344878.

Almost surely, 2^21965366646 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21965366646, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25389346752).

21965366646 is an abundant number, since it is smaller than the sum of its proper divisors (28813326858).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21965366646 is a wasteful number, since it uses less digits than its factorization.

21965366646 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16707 (or 16698 counting only the distinct ones).

The product of its digits is 8398080, while the sum is 54.

The spelling of 21965366646 in words is "twenty-one billion, nine hundred sixty-five million, three hundred sixty-six thousand, six hundred forty-six".