18961543 has 4 divisors (see below), whose sum is σ = 19041120. Its totient is φ = 18881968.

The previous prime is 18961529. The next prime is 18961559. The reversal of 18961543 is 34516981.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 34516981 = 31 ⋅1113451.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18961543 is a prime.

It is a super-2 number, since 2×18961543² = 719080225881698, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18961573) 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, 39430 + ... + 39907.

It is an arithmetic number, because the mean of its divisors is an integer number (4760280).

Almost surely, 2^18961543 is an apocalyptic number.

18961543 is a deficient number, since it is larger than the sum of its proper divisors (79577).

18961543 is an equidigital number, since it uses as much as digits as its factorization.

18961543 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79576.

The product of its digits is 25920, while the sum is 37.

The square root of 18961543 is about 4354.4853886539. The cubic root of 18961543 is about 266.6600104241.

The spelling of 18961543 in words is "eighteen million, nine hundred sixty-one thousand, five hundred forty-three".