1215591 has 16 divisors (see below), whose sum is σ = 1774080. Its totient is φ = 735840.

The previous prime is 1215587. The next prime is 1215623. The reversal of 1215591 is 1955121.

It is not a de Polignac number, because 1215591 - 2² = 1215587 is a prime.

It is a super-2 number, since 2×1215591² = 2955322958562, which contains 22 as substring.

1215591 is a lucky number.

It is a plaindrome in base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1215521) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2550 + ... + 2988.

It is an arithmetic number, because the mean of its divisors is an integer number (110880).

2^1215591 is an apocalyptic number.

1215591 is a deficient number, since it is larger than the sum of its proper divisors (558489).

1215591 is a wasteful number, since it uses less digits than its factorization.

1215591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 526.

The product of its digits is 450, while the sum is 24.

The square root of 1215591 is about 1102.5384347042. The cubic root of 1215591 is about 106.7240977618.

It can be divided in two parts, 12155 and 91, that added together give a triangular number (12246 = T₁₅₆).

The spelling of 1215591 in words is "one million, two hundred fifteen thousand, five hundred ninety-one".