1551315581 has 4 divisors (see below), whose sum is σ = 1551396000. Its totient is φ = 1551235164.

The previous prime is 1551315551. The next prime is 1551315593. The reversal of 1551315581 is 1855131551.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, 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 1551315581 - 2⁶ = 1551315517 is a prime.

It is a super-2 number, since 2×1551315581² = 4813160063706735122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1551315551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7970 + ... + 56268.

It is an arithmetic number, because the mean of its divisors is an integer number (387849000).

Almost surely, 2^1551315581 is an apocalyptic number.

It is an amenable number.

1551315581 is a deficient number, since it is larger than the sum of its proper divisors (80419).

1551315581 is an equidigital number, since it uses as much as digits as its factorization.

1551315581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80418.

The product of its digits is 15000, while the sum is 35.

The square root of 1551315581 is about 39386.7437217143. The cubic root of 1551315581 is about 1157.6218571863.

The spelling of 1551315581 in words is "one billion, five hundred fifty-one million, three hundred fifteen thousand, five hundred eighty-one".