1561261216 has 12 divisors (see below), whose sum is σ = 3073733082. Its totient is φ = 780630592.

The previous prime is 1561261151. The next prime is 1561261237. The reversal of 1561261216 is 6121621651.

It can be written as a sum of positive squares in only one way, i.e., 1376410000 + 184851216 = 37100^2 + 13596^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 24394675 + ... + 24394738.

Almost surely, 2^1561261216 is an apocalyptic number.

1561261216 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

1561261216 is a deficient number, since it is larger than the sum of its proper divisors (1512471866).

1561261216 is an equidigital number, since it uses as much as digits as its factorization.

1561261216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48789423 (or 48789415 counting only the distinct ones).

The product of its digits is 4320, while the sum is 31.

The square root of 1561261216 is about 39512.7981292138. The cubic root of 1561261216 is about 1160.0904646055.

Adding to 1561261216 its reverse (6121621651), we get a palindrome (7682882867).

The spelling of 1561261216 in words is "one billion, five hundred sixty-one million, two hundred sixty-one thousand, two hundred sixteen".