1561397 has 6 divisors (see below), whose sum is σ = 1588482. Its totient is φ = 1534752.

The previous prime is 1561393. The next prime is 1561421. The reversal of 1561397 is 7931651.

It can be written as a sum of positive squares in 3 ways, for example, as 703921 + 857476 = 839^2 + 926^2 .

It is not a de Polignac number, because 1561397 - 2² = 1561393 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1561393) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 5183 + ... + 5475.

It is an arithmetic number, because the mean of its divisors is an integer number (264747).

2^1561397 is an apocalyptic number.

It is an amenable number.

1561397 is a deficient number, since it is larger than the sum of its proper divisors (27085).

1561397 is an frugal number, since it uses more digits than its factorization.

1561397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 439 (or 366 counting only the distinct ones).

The product of its digits is 5670, while the sum is 32.

The square root of 1561397 is about 1249.5587221095. The cubic root of 1561397 is about 116.0124094929.

The spelling of 1561397 in words is "one million, five hundred sixty-one thousand, three hundred ninety-seven".