66821748 has 96 divisors (see below), whose sum is σ = 184396800. Its totient is φ = 18441216.

The previous prime is 66821743. The next prime is 66821813. The reversal of 66821748 is 84712866.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66821743) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 480663 + ... + 480801.

It is an arithmetic number, because the mean of its divisors is an integer number (1920800).

Almost surely, 2^66821748 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 66821748, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (92198400).

66821748 is an abundant number, since it is smaller than the sum of its proper divisors (117575052).

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

66821748 is a wasteful number, since it uses less digits than its factorization.

66821748 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 309 (or 307 counting only the distinct ones).

The product of its digits is 129024, while the sum is 42.

The square root of 66821748 is about 8174.4570461897. The cubic root of 66821748 is about 405.7943015540.

The spelling of 66821748 in words is "sixty-six million, eight hundred twenty-one thousand, seven hundred forty-eight".