660721541 has 8 divisors (see below), whose sum is σ = 700038144. Its totient is φ = 621455040.

The previous prime is 660721517. The next prime is 660721547. The reversal of 660721541 is 145127066.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-660721541 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 660721498 and 660721507.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (660721547) 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, 16586 + ... + 39956.

It is an arithmetic number, because the mean of its divisors is an integer number (87504768).

Almost surely, 2^660721541 is an apocalyptic number.

It is an amenable number.

660721541 is a deficient number, since it is larger than the sum of its proper divisors (39316603).

660721541 is a wasteful number, since it uses less digits than its factorization.

660721541 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25051.

The product of its (nonzero) digits is 10080, while the sum is 32.

The square root of 660721541 is about 25704.5042939949. The cubic root of 660721541 is about 870.9759343733.

The spelling of 660721541 in words is "six hundred sixty million, seven hundred twenty-one thousand, five hundred forty-one".