66139990 has 16 divisors (see below), whose sum is σ = 136059552. Its totient is φ = 22676544.

The previous prime is 66139939. The next prime is 66139993. The reversal of 66139990 is 9993166.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66139993) 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, 472359 + ... + 472498.

It is an arithmetic number, because the mean of its divisors is an integer number (8503722).

Almost surely, 2^66139990 is an apocalyptic number.

66139990 is an abundant number, since it is smaller than the sum of its proper divisors (69919562).

66139990 is a wasteful number, since it uses less digits than its factorization.

66139990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 944871.

The product of its (nonzero) digits is 78732, while the sum is 43.

The square root of 66139990 is about 8132.6496297332. The cubic root of 66139990 is about 404.4095241210.

The spelling of 66139990 in words is "sixty-six million, one hundred thirty-nine thousand, nine hundred ninety".