728155917 has 12 divisors (see below), whose sum is σ = 1113650460. Its totient is φ = 456882048.

The previous prime is 728155889. The next prime is 728155921. The reversal of 728155917 is 719551827.

728155917 is a `hidden beast` number, since 7 + 2 + 81 + 559 + 17 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 404371881 + 323784036 = 20109^2 + 17994^2 .

It is not a de Polignac number, because 728155917 - 2⁶ = 728155853 is a prime.

It is a super-2 number, since 2×728155917² = 1060422078924221778, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (728155957) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2379442 + ... + 2379747.

It is an arithmetic number, because the mean of its divisors is an integer number (92804205).

Almost surely, 2^728155917 is an apocalyptic number.

It is an amenable number.

728155917 is a deficient number, since it is larger than the sum of its proper divisors (385494543).

728155917 is a wasteful number, since it uses less digits than its factorization.

728155917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4759212 (or 4759209 counting only the distinct ones).

The product of its digits is 176400, while the sum is 45.

The square root of 728155917 is about 26984.3643060199. The cubic root of 728155917 is about 899.6525065895.

The spelling of 728155917 in words is "seven hundred twenty-eight million, one hundred fifty-five thousand, nine hundred seventeen".