66406521456 has 240 divisors, whose sum is σ = 214982097408. Its totient is φ = 18911692800.

The previous prime is 66406521451. The next prime is 66406521457. The reversal of 66406521456 is 65412560466.

66406521456 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66406521451) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 24530055 + ... + 24532761.

Almost surely, 2^66406521456 is an apocalyptic number.

66406521456 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66406521456, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (107491048704).

66406521456 is an abundant number, since it is smaller than the sum of its proper divisors (148575575952).

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

66406521456 is a wasteful number, since it uses less digits than its factorization.

66406521456 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3660 (or 3651 counting only the distinct ones).

The product of its (nonzero) digits is 1036800, while the sum is 45.

The spelling of 66406521456 in words is "sixty-six billion, four hundred six million, five hundred twenty-one thousand, four hundred fifty-six".