66720621 has 8 divisors (see below), whose sum is σ = 97048224. Its totient is φ = 40436720.

The previous prime is 66720559. The next prime is 66720659. The reversal of 66720621 is 12602766.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 66720621 - 2⁹ = 66720109 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66720721) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1010886 + ... + 1010951.

It is an arithmetic number, because the mean of its divisors is an integer number (12131028).

Almost surely, 2^66720621 is an apocalyptic number.

It is an amenable number.

66720621 is a deficient number, since it is larger than the sum of its proper divisors (30327603).

66720621 is a wasteful number, since it uses less digits than its factorization.

66720621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2021851.

The product of its (nonzero) digits is 6048, while the sum is 30.

The square root of 66720621 is about 8168.2691557024. The cubic root of 66720621 is about 405.5894905933.

The spelling of 66720621 in words is "sixty-six million, seven hundred twenty thousand, six hundred twenty-one".