66397940 has 48 divisors (see below), whose sum is σ = 162624000. Its totient is φ = 22762656.

The previous prime is 66397921. The next prime is 66397949. The reversal of 66397940 is 4979366.

It is a junction number, because it is equal to n+sod(n) for n = 66397891 and 66397900.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66397949) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2021 + ... + 11699.

It is an arithmetic number, because the mean of its divisors is an integer number (3388000).

Almost surely, 2^66397940 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 66397940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (81312000).

66397940 is an abundant number, since it is smaller than the sum of its proper divisors (96226060).

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

66397940 is a wasteful number, since it uses less digits than its factorization.

66397940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9709 (or 9693 counting only the distinct ones).

The product of its (nonzero) digits is 244944, while the sum is 44.

The square root of 66397940 is about 8148.4931122263. The cubic root of 66397940 is about 404.9345827380.

The spelling of 66397940 in words is "sixty-six million, three hundred ninety-seven thousand, nine hundred forty".