66407220 has 108 divisors (see below), whose sum is σ = 221484900. Its totient is φ = 16093440.

The previous prime is 66407213. The next prime is 66407227. The reversal of 66407220 is 2270466.

66407220 = 680² + 681² + ... + 800².

It is an interprime number because it is at equal distance from previous prime (66407213) and next prime (66407227).

It can be written as a sum of positive squares in 2 ways, for example, as 14653584 + 51753636 = 3828^2 + 7194^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66407227) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 20256 + ... + 23304.

Almost surely, 2^66407220 is an apocalyptic number.

66407220 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 66407220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (110742450).

66407220 is an abundant number, since it is smaller than the sum of its proper divisors (155077680).

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

66407220 is a wasteful number, since it uses less digits than its factorization.

66407220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3086 (or 3070 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 27.

The square root of 66407220 is about 8149.0625227691. The cubic root of 66407220 is about 404.9534468668.

Adding to 66407220 its reverse (2270466), we get a palindrome (68677686).

The spelling of 66407220 in words is "sixty-six million, four hundred seven thousand, two hundred twenty".