15478921 has 2 divisors, whose sum is σ = 15478922. Its totient is φ = 15478920.

The previous prime is 15478909. The next prime is 15478927. The reversal of 15478921 is 12987451.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12503296 + 2975625 = 3536^2 + 1725^2 .

It is a cyclic number.

It is not a de Polignac number, because 15478921 - 2¹¹ = 15476873 is a prime.

It is not a weakly prime, because it can be changed into another prime (15478927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7739460 + 7739461.

It is an arithmetic number, because the mean of its divisors is an integer number (7739461).

Almost surely, 2^15478921 is an apocalyptic number.

It is an amenable number.

15478921 is a deficient number, since it is larger than the sum of its proper divisors (1).

15478921 is an equidigital number, since it uses as much as digits as its factorization.

15478921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 20160, while the sum is 37.

The square root of 15478921 is about 3934.3259905605. The cubic root of 15478921 is about 249.2184713980.

The spelling of 15478921 in words is "fifteen million, four hundred seventy-eight thousand, nine hundred twenty-one".