66637890 has 128 divisors (see below), whose sum is σ = 196957440. Its totient is φ = 16096320.

The previous prime is 66637889. The next prime is 66637891. The reversal of 66637890 is 9873666.

It is an interprime number because it is at equal distance from previous prime (66637889) and next prime (66637891).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (66637891) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 240432 + ... + 240708.

It is an arithmetic number, because the mean of its divisors is an integer number (1538730).

Almost surely, 2^66637890 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66637890, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (98478720).

66637890 is an abundant number, since it is smaller than the sum of its proper divisors (130319550).

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

66637890 is a wasteful number, since it uses less digits than its factorization.

66637890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 316 (or 298 counting only the distinct ones).

The product of its (nonzero) digits is 326592, while the sum is 45.

The square root of 66637890 is about 8163.2034153266. The cubic root of 66637890 is about 405.4217828087.

The spelling of 66637890 in words is "sixty-six million, six hundred thirty-seven thousand, eight hundred ninety".