1215261787 has 4 divisors (see below), whose sum is σ = 1268099280. Its totient is φ = 1162424296.

The previous prime is 1215261769. The next prime is 1215261851. The reversal of 1215261787 is 7871625121.

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 1215261787 - 2¹⁵ = 1215229019 is a prime.

It is a super-2 number, since 2×1215261787² = 2953722421884866738, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1215261737) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26418712 + ... + 26418757.

It is an arithmetic number, because the mean of its divisors is an integer number (317024820).

Almost surely, 2^1215261787 is an apocalyptic number.

1215261787 is a deficient number, since it is larger than the sum of its proper divisors (52837493).

1215261787 is an equidigital number, since it uses as much as digits as its factorization.

1215261787 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52837492.

The product of its digits is 47040, while the sum is 40.

The square root of 1215261787 is about 34860.6050865443. The cubic root of 1215261787 is about 1067.1446235741.

The spelling of 1215261787 in words is "one billion, two hundred fifteen million, two hundred sixty-one thousand, seven hundred eighty-seven".