66721489 has 8 divisors (see below), whose sum is σ = 69969960. Its totient is φ = 63536256.

The previous prime is 66721477. The next prime is 66721493. The reversal of 66721489 is 98412766.

It can be written as a sum of positive squares in 4 ways, for example, as 3359889 + 63361600 = 1833^2 + 7960^2 .

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 66721489 - 2⁹ = 66720977 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66721409) 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, 13642 + ... + 17875.

It is an arithmetic number, because the mean of its divisors is an integer number (8746245).

Almost surely, 2^66721489 is an apocalyptic number.

It is an amenable number.

66721489 is a deficient number, since it is larger than the sum of its proper divisors (3248471).

66721489 is a wasteful number, since it uses less digits than its factorization.

66721489 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31619.

The product of its digits is 145152, while the sum is 43.

The square root of 66721489 is about 8168.3222879610. The cubic root of 66721489 is about 405.5912494206.

The spelling of 66721489 in words is "sixty-six million, seven hundred twenty-one thousand, four hundred eighty-nine".