1523721 has 4 divisors (see below), whose sum is σ = 2031632. Its totient is φ = 1015812.

The previous prime is 1523707. The next prime is 1523737. The reversal of 1523721 is 1273251.

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.

It is not a de Polignac number, because 1523721 - 2¹¹ = 1521673 is a prime.

It is a D-number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1523701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 253951 + ... + 253956.

It is an arithmetic number, because the mean of its divisors is an integer number (507908).

2^1523721 is an apocalyptic number.

It is an amenable number.

1523721 is a deficient number, since it is larger than the sum of its proper divisors (507911).

1523721 is an equidigital number, since it uses as much as digits as its factorization.

1523721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 507910.

The product of its digits is 420, while the sum is 21.

The square root of 1523721 is about 1234.3909429350. The cubic root of 1523721 is about 115.0716881314.

Adding to 1523721 its reverse (1273251), we get a palindrome (2796972).

The spelling of 1523721 in words is "one million, five hundred twenty-three thousand, seven hundred twenty-one".