66172420 has 12 divisors (see below), whose sum is σ = 138962124. Its totient is φ = 26468960.

The previous prime is 66172417. The next prime is 66172429. The reversal of 66172420 is 2427166.

66172420 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 47665216 + 18507204 = 6904^2 + 4302^2 .

It is not an unprimeable number, because it can be changed into a prime (66172429) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1654291 + ... + 1654330.

It is an arithmetic number, because the mean of its divisors is an integer number (11580177).

Almost surely, 2^66172420 is an apocalyptic number.

It is an amenable number.

66172420 is an abundant number, since it is smaller than the sum of its proper divisors (72789704).

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

66172420 is a wasteful number, since it uses less digits than its factorization.

66172420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3308630 (or 3308628 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 28.

The square root of 66172420 is about 8134.6432005344. The cubic root of 66172420 is about 404.4756105029.

Adding to 66172420 its reverse (2427166), we get a palindrome (68599586).

It can be divided in two parts, 66172 and 420, that multiplied together give a triangular number (27792240 = T₇₄₅₅).

The spelling of 66172420 in words is "sixty-six million, one hundred seventy-two thousand, four hundred twenty".