1221615 has 16 divisors (see below), whose sum is σ = 2172000. Its totient is φ = 651456.

The previous prime is 1221601. The next prime is 1221631. The reversal of 1221615 is 5161221.

It is not a de Polignac number, because 1221615 - 2⁶ = 1221551 is a prime.

1221615 is a lucky number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4390 + ... + 4659.

It is an arithmetic number, because the mean of its divisors is an integer number (135750).

2^1221615 is an apocalyptic number.

1221615 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1221615 is a deficient number, since it is larger than the sum of its proper divisors (950385).

1221615 is an equidigital number, since it uses as much as digits as its factorization.

1221615 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9063 (or 9057 counting only the distinct ones).

The product of its digits is 120, while the sum is 18.

The square root of 1221615 is about 1105.2669360838. The cubic root of 1221615 is about 106.9001018293.

Adding to 1221615 its reverse (5161221), we get a palindrome (6382836).

The spelling of 1221615 in words is "one million, two hundred twenty-one thousand, six hundred fifteen".