66431540 has 48 divisors (see below), whose sum is σ = 161384832. Its totient is φ = 22498176.

The previous prime is 66431531. The next prime is 66431549. The reversal of 66431540 is 4513466.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (66431531) and next prime (66431549).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66431549) 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, 8762 + ... + 14478.

It is an arithmetic number, because the mean of its divisors is an integer number (3362184).

Almost surely, 2^66431540 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 66431540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (80692416).

66431540 is an abundant number, since it is smaller than the sum of its proper divisors (94953292).

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

66431540 is a wasteful number, since it uses less digits than its factorization.

66431540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5816 (or 5814 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 29.

The square root of 66431540 is about 8150.5545823582. The cubic root of 66431540 is about 405.0028755575.

The spelling of 66431540 in words is "sixty-six million, four hundred thirty-one thousand, five hundred forty".