66721734 has 48 divisors (see below), whose sum is σ = 150733440. Its totient is φ = 21306240.

The previous prime is 66721729. The next prime is 66721747. The reversal of 66721734 is 43712766.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Curzon number.

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, 60274 + ... + 61370.

It is an arithmetic number, because the mean of its divisors is an integer number (3140280).

Almost surely, 2^66721734 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66721734, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (75366720).

66721734 is an abundant number, since it is smaller than the sum of its proper divisors (84011706).

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

66721734 is a wasteful number, since it uses less digits than its factorization.

66721734 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1245 (or 1242 counting only the distinct ones).

The product of its digits is 42336, while the sum is 36.

The square root of 66721734 is about 8168.3372849069. The cubic root of 66721734 is about 405.5917458610.

The spelling of 66721734 in words is "sixty-six million, seven hundred twenty-one thousand, seven hundred thirty-four".