1561886671 has 4 divisors (see below), whose sum is σ = 1612270144. Its totient is φ = 1511503200.

The previous prime is 1561886663. The next prime is 1561886681. The reversal of 1561886671 is 1766881651.

It is a happy number.

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 1561886671 - 2³ = 1561886663 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 (1561886681) 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, 25191690 + ... + 25191751.

It is an arithmetic number, because the mean of its divisors is an integer number (403067536).

Almost surely, 2^1561886671 is an apocalyptic number.

1561886671 is a deficient number, since it is larger than the sum of its proper divisors (50383473).

1561886671 is an equidigital number, since it uses as much as digits as its factorization.

1561886671 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50383472.

The product of its digits is 483840, while the sum is 49.

The square root of 1561886671 is about 39520.7119242556. The cubic root of 1561886671 is about 1160.2453580775.

The spelling of 1561886671 in words is "one billion, five hundred sixty-one million, eight hundred eighty-six thousand, six hundred seventy-one".