66638580 has 24 divisors (see below), whose sum is σ = 186588192. Its totient is φ = 17770272.

The previous prime is 66638573. The next prime is 66638587. The reversal of 66638580 is 8583666.

It is an interprime number because it is at equal distance from previous prime (66638573) and next prime (66638587).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66638587) 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, 555262 + ... + 555381.

It is an arithmetic number, because the mean of its divisors is an integer number (7774508).

Almost surely, 2^66638580 is an apocalyptic number.

66638580 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

66638580 is an abundant number, since it is smaller than the sum of its proper divisors (119949612).

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

66638580 is a wasteful number, since it uses less digits than its factorization.

66638580 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1110655 (or 1110653 counting only the distinct ones).

The product of its (nonzero) digits is 207360, while the sum is 42.

The square root of 66638580 is about 8163.2456780376. The cubic root of 66638580 is about 405.4231821130.

The spelling of 66638580 in words is "sixty-six million, six hundred thirty-eight thousand, five hundred eighty".