66651858 has 72 divisors (see below), whose sum is σ = 180943308. Its totient is φ = 17575488.

The previous prime is 66651857. The next prime is 66651859. The reversal of 66651858 is 85815666.

It is an interprime number because it is at equal distance from previous prime (66651857) and next prime (66651859).

It can be written as a sum of positive squares in 2 ways, for example, as 66048129 + 603729 = 8127^2 + 777^2 .

It is not an unprimeable number, because it can be changed into a prime (66651857) 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, 8560 + ... + 14372.

Almost surely, 2^66651858 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66651858, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (90471654).

66651858 is an abundant number, since it is smaller than the sum of its proper divisors (114291450).

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

66651858 is a wasteful number, since it uses less digits than its factorization.

66651858 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5848 (or 5838 counting only the distinct ones).

The product of its digits is 345600, while the sum is 45.

The square root of 66651858 is about 8164.0589169849. The cubic root of 66651858 is about 405.4501077143.

The spelling of 66651858 in words is "sixty-six million, six hundred fifty-one thousand, eight hundred fifty-eight".