1251786987 has 36 divisors (see below), whose sum is σ = 2041714920. Its totient is φ = 757433160.

The previous prime is 1251786961. The next prime is 1251787079. The reversal of 1251786987 is 7896871521.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It is not a de Polignac number, because 1251786987 - 2¹⁴ = 1251770603 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1251706987) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 2021964 + ... + 2022582.

Almost surely, 2^1251786987 is an apocalyptic number.

1251786987 is a deficient number, since it is larger than the sum of its proper divisors (789927933).

1251786987 is an frugal number, since it uses more digits than its factorization.

1251786987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1269 (or 633 counting only the distinct ones).

The product of its digits is 1693440, while the sum is 54.

The square root of 1251786987 is about 35380.6018462095. The cubic root of 1251786987 is about 1077.7304268325.

The spelling of 1251786987 in words is "one billion, two hundred fifty-one million, seven hundred eighty-six thousand, nine hundred eighty-seven".