66440278 has 4 divisors (see below), whose sum is σ = 99660420. Its totient is φ = 33220138.

The previous prime is 66440273. The next prime is 66440287. The reversal of 66440278 is 87204466.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66440273) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 16610068 + ... + 16610071.

It is an arithmetic number, because the mean of its divisors is an integer number (24915105).

Almost surely, 2^66440278 is an apocalyptic number.

66440278 is a deficient number, since it is larger than the sum of its proper divisors (33220142).

66440278 is a wasteful number, since it uses less digits than its factorization.

66440278 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33220141.

The product of its (nonzero) digits is 64512, while the sum is 37.

The square root of 66440278 is about 8151.0906018765. The cubic root of 66440278 is about 405.0206319825.

The spelling of 66440278 in words is "sixty-six million, four hundred forty thousand, two hundred seventy-eight".