66689980 has 72 divisors (see below), whose sum is σ = 172540368. Its totient is φ = 21514752.

The previous prime is 66689969. The next prime is 66689999. The reversal of 66689980 is 8998666.

66689980 = T₁₅₁ + T₁₅₂ + ... + T₇₃₈.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 14659 + ... + 18661.

It is an arithmetic number, because the mean of its divisors is an integer number (2396394).

Almost surely, 2^66689980 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66689980, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (86270184).

66689980 is an abundant number, since it is smaller than the sum of its proper divisors (105850388).

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

66689980 is a wasteful number, since it uses less digits than its factorization.

66689980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4043 (or 4034 counting only the distinct ones).

The product of its (nonzero) digits is 1119744, while the sum is 52.

The square root of 66689980 is about 8166.3933287590. The cubic root of 66689980 is about 405.5273929972.

The spelling of 66689980 in words is "sixty-six million, six hundred eighty-nine thousand, nine hundred eighty".