15421997 has 4 divisors (see below), whose sum is σ = 15953820. Its totient is φ = 14890176.

The previous prime is 15421979. The next prime is 15421999. The reversal of 15421997 is 79912451.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 79912451 = 31 ⋅2577821.

It can be written as a sum of positive squares in 2 ways, for example, as 2669956 + 12752041 = 1634^2 + 3571^2 .

It is a cyclic number.

It is not a de Polignac number, because 15421997 - 2¹² = 15417901 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 15421997.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15421999) 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, 265868 + ... + 265925.

It is an arithmetic number, because the mean of its divisors is an integer number (3988455).

Almost surely, 2^15421997 is an apocalyptic number.

It is an amenable number.

15421997 is a deficient number, since it is larger than the sum of its proper divisors (531823).

15421997 is an equidigital number, since it uses as much as digits as its factorization.

15421997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 531822.

The product of its digits is 22680, while the sum is 38.

The square root of 15421997 is about 3927.0850512817. The cubic root of 15421997 is about 248.9125943871.

The spelling of 15421997 in words is "fifteen million, four hundred twenty-one thousand, nine hundred ninety-seven".