66455640 has 224 divisors, whose sum is σ = 233727120. Its totient is φ = 16982784.

The previous prime is 66455591. The next prime is 66455651. The reversal of 66455640 is 4655466.

66455640 = 199³ + 200³ + ... + 206³.

It is a happy number.

66455640 is a `hidden beast` number, since 6 + 6 + 4 + 5 + 5 + 640 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 66455595 and 66455604.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 1253854 + ... + 1253906.

Almost surely, 2^66455640 is an apocalyptic number.

66455640 is a gapful number since it is divisible by the number (60) 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 66455640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (116863560).

66455640 is an abundant number, since it is smaller than the sum of its proper divisors (167271480).

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

66455640 is a wasteful number, since it uses less digits than its factorization.

66455640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 125 (or 106 counting only the distinct ones).

The product of its (nonzero) digits is 86400, while the sum is 36.

The square root of 66455640 is about 8152.0328753017. The cubic root of 66455640 is about 405.0518452147.

The spelling of 66455640 in words is "sixty-six million, four hundred fifty-five thousand, six hundred forty".