61781143 has 4 divisors (see below), whose sum is σ = 62418160. Its totient is φ = 61144128.

The previous prime is 61781129. The next prime is 61781177. The reversal of 61781143 is 34118716.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 61781143 - 2²⁵ = 28226711 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 (61781113) 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, 318363 + ... + 318556.

It is an arithmetic number, because the mean of its divisors is an integer number (15604540).

Almost surely, 2^61781143 is an apocalyptic number.

61781143 is a deficient number, since it is larger than the sum of its proper divisors (637017).

61781143 is an equidigital number, since it uses as much as digits as its factorization.

61781143 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 637016.

The product of its digits is 4032, while the sum is 31.

The square root of 61781143 is about 7860.0981546034. The cubic root of 61781143 is about 395.3229063892.

Adding to 61781143 its reverse (34118716), we get a palindrome (95899859).

The spelling of 61781143 in words is "sixty-one million, seven hundred eighty-one thousand, one hundred forty-three".