66721726 has 4 divisors (see below), whose sum is σ = 100082592. Its totient is φ = 33360862.

The previous prime is 66721723. The next prime is 66721727. The reversal of 66721726 is 62712766.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66721723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 16680430 + ... + 16680433.

It is an arithmetic number, because the mean of its divisors is an integer number (25020648).

Almost surely, 2^66721726 is an apocalyptic number.

66721726 is a deficient number, since it is larger than the sum of its proper divisors (33360866).

66721726 is a wasteful number, since it uses less digits than its factorization.

66721726 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33360865.

The product of its digits is 42336, while the sum is 37.

The square root of 66721726 is about 8168.3367952111. The cubic root of 66721726 is about 405.5917296507.

The spelling of 66721726 in words is "sixty-six million, seven hundred twenty-one thousand, seven hundred twenty-six".