1331561987 has 8 divisors (see below), whose sum is σ = 1526588256. Its totient is φ = 1137736512.

The previous prime is 1331561947. The next prime is 1331561993. The reversal of 1331561987 is 7891651331.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1331561987 - 2¹⁰ = 1331560963 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1331561927) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 297818 + ... + 302255.

It is an arithmetic number, because the mean of its divisors is an integer number (190823532).

Almost surely, 2^1331561987 is an apocalyptic number.

1331561987 is a deficient number, since it is larger than the sum of its proper divisors (195026269).

1331561987 is an equidigital number, since it uses as much as digits as its factorization.

1331561987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 600397.

The product of its digits is 136080, while the sum is 44.

The square root of 1331561987 is about 36490.5739472538. The cubic root of 1331561987 is about 1100.1547955710.

The spelling of 1331561987 in words is "one billion, three hundred thirty-one million, five hundred sixty-one thousand, nine hundred eighty-seven".