66699780 has 120 divisors (see below), whose sum is σ = 218343552. Its totient is φ = 15212736.

The previous prime is 66699761. The next prime is 66699781. The reversal of 66699780 is 8799666.

It is a happy number.

It is a super-4 number, since 4×66699780⁴ (a number of 32 digits) contains 4444 as substring.

It is not an unprimeable number, because it can be changed into a prime (66699781) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 143829 + ... + 144291.

Almost surely, 2^66699780 is an apocalyptic number.

66699780 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66699780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (109171776).

66699780 is an abundant number, since it is smaller than the sum of its proper divisors (151643772).

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

66699780 is a wasteful number, since it uses less digits than its factorization.

66699780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 503 (or 480 counting only the distinct ones).

The product of its (nonzero) digits is 979776, while the sum is 51.

The square root of 66699780 is about 8166.9933268003. The cubic root of 66699780 is about 405.5472559202.

The spelling of 66699780 in words is "sixty-six million, six hundred ninety-nine thousand, seven hundred eighty".