15721481 has 4 divisors (see below), whose sum is σ = 16646292. Its totient is φ = 14796672.

The previous prime is 15721463. The next prime is 15721487. The reversal of 15721481 is 18412751.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12187081 + 3534400 = 3491^2 + 1880^2 .

It is a cyclic number.

It is not a de Polignac number, because 15721481 - 2¹⁰ = 15720457 is a prime.

It is a super-2 number, since 2×15721481² = 494329929666722, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (15721487) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 462380 + ... + 462413.

It is an arithmetic number, because the mean of its divisors is an integer number (4161573).

Almost surely, 2^15721481 is an apocalyptic number.

It is an amenable number.

15721481 is a deficient number, since it is larger than the sum of its proper divisors (924811).

15721481 is an equidigital number, since it uses as much as digits as its factorization.

15721481 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 924810.

The product of its digits is 2240, while the sum is 29.

The square root of 15721481 is about 3965.0322823402. The cubic root of 15721481 is about 250.5135098417.

The spelling of 15721481 in words is "fifteen million, seven hundred twenty-one thousand, four hundred eighty-one".