66891616 has 48 divisors (see below), whose sum is σ = 144365760. Its totient is φ = 30257280.

The previous prime is 66891589. The next prime is 66891637. The reversal of 66891616 is 61619866.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 107755 + ... + 108373.

It is an arithmetic number, because the mean of its divisors is an integer number (3007620).

Almost surely, 2^66891616 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 66891616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (72182880).

66891616 is an abundant number, since it is smaller than the sum of its proper divisors (77474144).

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

66891616 is a wasteful number, since it uses less digits than its factorization.

66891616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 947 (or 939 counting only the distinct ones).

The product of its digits is 93312, while the sum is 43.

The square root of 66891616 is about 8178.7294856842. The cubic root of 66891616 is about 405.9356834710.

The spelling of 66891616 in words is "sixty-six million, eight hundred ninety-one thousand, six hundred sixteen".