1561880851 has 4 divisors (see below), whose sum is σ = 1561975000. Its totient is φ = 1561786704.

The previous prime is 1561880839. The next prime is 1561880861. The reversal of 1561880851 is 1580881651.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1580881651 = 1321 ⋅1196731.

It is a cyclic number.

It is not a de Polignac number, because 1561880851 - 2⁹ = 1561880339 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1561880798 and 1561880807.

It is not an unprimeable number, because it can be changed into a prime (1561880821) 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, 14826 + ... + 57823.

It is an arithmetic number, because the mean of its divisors is an integer number (390493750).

Almost surely, 2^1561880851 is an apocalyptic number.

1561880851 is a deficient number, since it is larger than the sum of its proper divisors (94149).

1561880851 is an equidigital number, since it uses as much as digits as its factorization.

1561880851 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94148.

The product of its (nonzero) digits is 76800, while the sum is 43.

The square root of 1561880851 is about 39520.6382919102. The cubic root of 1561880851 is about 1160.2439169494.

It can be divided in two parts, 15618 and 80851, that added together give a palindrome (96469).

The spelling of 1561880851 in words is "one billion, five hundred sixty-one million, eight hundred eighty thousand, eight hundred fifty-one".