545165721 has 20 divisors (see below), whose sum is σ = 840657664. Its totient is φ = 351718200.

The previous prime is 545165717. The next prime is 545165729. The reversal of 545165721 is 127561545.

It is not a de Polignac number, because 545165721 - 2² = 545165717 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (545165729) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 106045 + ... + 111066.

Almost surely, 2^545165721 is an apocalyptic number.

It is an amenable number.

545165721 is a deficient number, since it is larger than the sum of its proper divisors (295491943).

545165721 is a wasteful number, since it uses less digits than its factorization.

545165721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 217154 (or 217145 counting only the distinct ones).

The product of its digits is 42000, while the sum is 36.

The square root of 545165721 is about 23348.7841439335. The cubic root of 545165721 is about 816.9137013229.

The spelling of 545165721 in words is "five hundred forty-five million, one hundred sixty-five thousand, seven hundred twenty-one".