15520421 has 8 divisors (see below), whose sum is σ = 17813760. Its totient is φ = 13246128.

The previous prime is 15520411. The next prime is 15520447. The reversal of 15520421 is 12402551.

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

It is not a de Polignac number, because 15520421 - 2⁶ = 15520357 is a prime.

It is a Duffinian number.

It is a plaindrome in base 15.

It is a junction number, because it is equal to n+sod(n) for n = 15520393 and 15520402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15520411) 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 7 ways as a sum of consecutive naturals, for example, 2966 + ... + 6311.

It is an arithmetic number, because the mean of its divisors is an integer number (2226720).

Almost surely, 2^15520421 is an apocalyptic number.

It is an amenable number.

15520421 is a deficient number, since it is larger than the sum of its proper divisors (2293339).

15520421 is an equidigital number, since it uses as much as digits as its factorization.

15520421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9523.

The product of its (nonzero) digits is 400, while the sum is 20.

The square root of 15520421 is about 3939.5965529480. The cubic root of 15520421 is about 249.4409963245.

Adding to 15520421 its reverse (12402551), we get a palindrome (27922972).

The spelling of 15520421 in words is "fifteen million, five hundred twenty thousand, four hundred twenty-one".