21195202644 has 324 divisors, whose sum is σ = 68987100000. Its totient is φ = 5466605760.

The previous prime is 21195202643. The next prime is 21195202661. The reversal of 21195202644 is 44620259112.

It is a happy number.

21195202644 is a `hidden beast` number, since 2 + 1 + 1 + 9 + 5 + 2 + 0 + 2 + 644 = 666.

It is a super-3 number, since 3×21195202644³ (a number of 32 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21195202599 and 21195202608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21195202643) by changing a digit.

It is a polite number, since it can be written in 107 ways as a sum of consecutive naturals, for example, 42475107 + ... + 42475605.

Almost surely, 2^21195202644 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21195202644, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34493550000).

21195202644 is an abundant number, since it is smaller than the sum of its proper divisors (47791897356).

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

21195202644 is a wasteful number, since it uses less digits than its factorization.

21195202644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 744 (or 721 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

The spelling of 21195202644 in words is "twenty-one billion, one hundred ninety-five million, two hundred two thousand, six hundred forty-four".