1561543 has 4 divisors (see below), whose sum is σ = 1583008. Its totient is φ = 1540080.

The previous prime is 1561541. The next prime is 1561559. The reversal of 1561543 is 3451651.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 3451651 = 7 ⋅493093.

It is a cyclic number.

It is not a de Polignac number, because 1561543 - 2¹ = 1561541 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 (1561541) 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, 10623 + ... + 10768.

It is an arithmetic number, because the mean of its divisors is an integer number (395752).

2^1561543 is an apocalyptic number.

1561543 is a deficient number, since it is larger than the sum of its proper divisors (21465).

1561543 is an equidigital number, since it uses as much as digits as its factorization.

1561543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21464.

The product of its digits is 1800, while the sum is 25.

The square root of 1561543 is about 1249.6171413677. The cubic root of 1561543 is about 116.0160253326.

The spelling of 1561543 in words is "one million, five hundred sixty-one thousand, five hundred forty-three".