1561437331 has 4 divisors (see below), whose sum is σ = 1561552792. Its totient is φ = 1561321872.

The previous prime is 1561437329. The next prime is 1561437349. The reversal of 1561437331 is 1337341651.

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.

It is a cyclic number.

It is not a de Polignac number, because 1561437331 - 2¹ = 1561437329 is a prime.

It is a super-2 number, since 2×1561437331² = 4876173077280807122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1561437391) 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, 34266 + ... + 65551.

It is an arithmetic number, because the mean of its divisors is an integer number (390388198).

Almost surely, 2^1561437331 is an apocalyptic number.

1561437331 is a deficient number, since it is larger than the sum of its proper divisors (115461).

1561437331 is an equidigital number, since it uses as much as digits as its factorization.

1561437331 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 115460.

The product of its digits is 22680, while the sum is 34.

The square root of 1561437331 is about 39515.0266480993. The cubic root of 1561437331 is about 1160.1340835396.

Adding to 1561437331 its reverse (1337341651), we get a palindrome (2898778982).

The spelling of 1561437331 in words is "one billion, five hundred sixty-one million, four hundred thirty-seven thousand, three hundred thirty-one".