66401240 has 32 divisors (see below), whose sum is σ = 149640480. Its totient is φ = 26518272.

The previous prime is 66401239. The next prime is 66401243. The reversal of 66401240 is 4210466.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66401243) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 40517 + ... + 42123.

It is an arithmetic number, because the mean of its divisors is an integer number (4676265).

Almost surely, 2^66401240 is an apocalyptic number.

It is an amenable number.

66401240 is an abundant number, since it is smaller than the sum of its proper divisors (83239240).

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

66401240 is a wasteful number, since it uses less digits than its factorization.

66401240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2651 (or 2647 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 23.

The square root of 66401240 is about 8148.6956011376. The cubic root of 66401240 is about 404.9412910886.

The spelling of 66401240 in words is "sixty-six million, four hundred one thousand, two hundred forty".