1518721 has 4 divisors (see below), whose sum is σ = 1567744. Its totient is φ = 1469700.

The previous prime is 1518709. The next prime is 1518731. The reversal of 1518721 is 1278151.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1278151 = 7 ⋅182593.

It is a cyclic number.

It is not a de Polignac number, because 1518721 - 2¹⁷ = 1387649 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1518731) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24465 + ... + 24526.

It is an arithmetic number, because the mean of its divisors is an integer number (391936).

2^1518721 is an apocalyptic number.

It is an amenable number.

1518721 is a deficient number, since it is larger than the sum of its proper divisors (49023).

1518721 is an equidigital number, since it uses as much as digits as its factorization.

1518721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49022.

The product of its digits is 560, while the sum is 25.

The square root of 1518721 is about 1232.3639884385. The cubic root of 1518721 is about 114.9456832338.

The spelling of 1518721 in words is "one million, five hundred eighteen thousand, seven hundred twenty-one".