1215891 has 20 divisors (see below), whose sum is σ = 1925352. Its totient is φ = 762048.

The previous prime is 1215881. The next prime is 1215899. The reversal of 1215891 is 1985121.

It is not a de Polignac number, because 1215891 - 2⁵ = 1215859 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (1215899) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 936 + ... + 1818.

2^1215891 is an apocalyptic number.

1215891 is a deficient number, since it is larger than the sum of its proper divisors (709461).

1215891 is an equidigital number, since it uses as much as digits as its factorization.

1215891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 912 (or 903 counting only the distinct ones).

The product of its digits is 720, while the sum is 27.

The square root of 1215891 is about 1102.6744759901. The cubic root of 1215891 is about 106.7328766455.

The spelling of 1215891 in words is "one million, two hundred fifteen thousand, eight hundred ninety-one".