669744447894 has 80 divisors (see below), whose sum is σ = 1529251511040. Its totient is φ = 219036389760.

The previous prime is 669744447851. The next prime is 669744447901. The reversal of 669744447894 is 498744447966.

669744447894 is a `hidden beast` number, since 6 + 6 + 97 + 4 + 4 + 447 + 8 + 94 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 2110512 + ... + 2407020.

It is an arithmetic number, because the mean of its divisors is an integer number (19115643888).

Almost surely, 2^669744447894 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 669744447894, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (764625755520).

669744447894 is an abundant number, since it is smaller than the sum of its proper divisors (859507063146).

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

669744447894 is a wasteful number, since it uses less digits than its factorization.

669744447894 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 296787 (or 296778 counting only the distinct ones).

The product of its digits is 1170505728, while the sum is 72.

Adding to 669744447894 its sum of digits (72), we get a palindrome (669744447966).

The spelling of 669744447894 in words is "six hundred sixty-nine billion, seven hundred forty-four million, four hundred forty-seven thousand, eight hundred ninety-four".