66138990 has 32 divisors (see below), whose sum is σ = 159213600. Its totient is φ = 17583744.

The previous prime is 66138979. The next prime is 66138991. The reversal of 66138990 is 9983166.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66138991) 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, 7312 + ... + 13628.

It is an arithmetic number, because the mean of its divisors is an integer number (4975425).

Almost surely, 2^66138990 is an apocalyptic number.

66138990 is an abundant number, since it is smaller than the sum of its proper divisors (93074610).

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

66138990 is a wasteful number, since it uses less digits than its factorization.

66138990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6676.

The product of its (nonzero) digits is 69984, while the sum is 42.

The square root of 66138990 is about 8132.5881489228. The cubic root of 66138990 is about 404.4074859614.

The spelling of 66138990 in words is "sixty-six million, one hundred thirty-eight thousand, nine hundred ninety".