1287639131 has 4 divisors (see below), whose sum is σ = 1287789600. Its totient is φ = 1287488664.

The previous prime is 1287639103. The next prime is 1287639137. The reversal of 1287639131 is 1319367821.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1287639131 is a prime.

It is a super-2 number, since 2×1287639131² = 3316029063364870322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1287639137) 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, 61571 + ... + 79788.

It is an arithmetic number, because the mean of its divisors is an integer number (321947400).

Almost surely, 2^1287639131 is an apocalyptic number.

1287639131 is a deficient number, since it is larger than the sum of its proper divisors (150469).

1287639131 is an equidigital number, since it uses as much as digits as its factorization.

1287639131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 150468.

The product of its digits is 54432, while the sum is 41.

The square root of 1287639131 is about 35883.6889268648. The cubic root of 1287639131 is about 1087.9227421690.

The spelling of 1287639131 in words is "one billion, two hundred eighty-seven million, six hundred thirty-nine thousand, one hundred thirty-one".