1551721515115 has 4 divisors (see below), whose sum is σ = 1862065818144. Its totient is φ = 1241377212088.

The previous prime is 1551721515107. The next prime is 1551721515119. The reversal of 1551721515115 is 5115151271551.

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 1551721515115 - 2³ = 1551721515107 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1551721515119) 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, 155172151507 + ... + 155172151516.

It is an arithmetic number, because the mean of its divisors is an integer number (465516454536).

Almost surely, 2^{1551721515115} is an apocalyptic number.

1551721515115 is a deficient number, since it is larger than the sum of its proper divisors (310344303029).

1551721515115 is an equidigital number, since it uses as much as digits as its factorization.

1551721515115 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 310344303028.

The product of its digits is 43750, while the sum is 40.

Adding to 1551721515115 its reverse (5115151271551), we get a palindrome (6666872786666).

The spelling of 1551721515115 in words is "one trillion, five hundred fifty-one billion, seven hundred twenty-one million, five hundred fifteen thousand, one hundred fifteen".