1561728706 has 8 divisors (see below), whose sum is σ = 2423372220. Its totient is φ = 753937968.

The previous prime is 1561728703. The next prime is 1561728733. The reversal of 1561728706 is 6078271651.

It can be written as a sum of positive squares in 2 ways, for example, as 1560645025 + 1083681 = 39505^2 + 1041^2 .

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

It is a super-2 number, since 2×1561728706² = 4877993102288868872, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1561728703) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13463121 + ... + 13463236.

Almost surely, 2^1561728706 is an apocalyptic number.

1561728706 is a deficient number, since it is larger than the sum of its proper divisors (861643514).

1561728706 is a wasteful number, since it uses less digits than its factorization.

1561728706 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26926388.

The product of its (nonzero) digits is 141120, while the sum is 43.

The square root of 1561728706 is about 39518.7133646833. The cubic root of 1561728706 is about 1160.2062420647.

The spelling of 1561728706 in words is "one billion, five hundred sixty-one million, seven hundred twenty-eight thousand, seven hundred six".