1215921 has 8 divisors (see below), whose sum is σ = 1852864. Its totient is φ = 694800.

The previous prime is 1215919. The next prime is 1215923. The reversal of 1215921 is 1295121.

It is an interprime number because it is at equal distance from previous prime (1215919) and next prime (1215923).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1215921 - 2¹ = 1215919 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21), and also a Moran number because the ratio is a prime number: 57901 = 1215921 / (1 + 2 + 1 + 5 + 9 + 2 + 1).

It is a Duffinian number.

It is a Curzon number.

1215921 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (1215923) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28930 + ... + 28971.

It is an arithmetic number, because the mean of its divisors is an integer number (231608).

2^1215921 is an apocalyptic number.

It is an amenable number.

1215921 is a deficient number, since it is larger than the sum of its proper divisors (636943).

1215921 is an equidigital number, since it uses as much as digits as its factorization.

1215921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57911.

The product of its digits is 180, while the sum is 21.

The square root of 1215921 is about 1102.6880791956. The cubic root of 1215921 is about 106.7337544544.

The spelling of 1215921 in words is "one million, two hundred fifteen thousand, nine hundred twenty-one".