13561921 has 4 divisors (see below), whose sum is σ = 13682052. Its totient is φ = 13441792.

The previous prime is 13561901. The next prime is 13561931. The reversal of 13561921 is 12916531.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12916531 = 523 ⋅24697.

It can be written as a sum of positive squares in 2 ways, for example, as 6076225 + 7485696 = 2465^2 + 2736^2 .

It is a cyclic number.

It is not a de Polignac number, because 13561921 - 2⁹ = 13561409 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 13561921.

It is not an unprimeable number, because it can be changed into a prime (13561901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 59896 + ... + 60121.

It is an arithmetic number, because the mean of its divisors is an integer number (3420513).

Almost surely, 2^13561921 is an apocalyptic number.

It is an amenable number.

13561921 is a deficient number, since it is larger than the sum of its proper divisors (120131).

13561921 is a wasteful number, since it uses less digits than its factorization.

13561921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 120130.

The product of its digits is 1620, while the sum is 28.

The square root of 13561921 is about 3682.6513546628. The cubic root of 13561921 is about 238.4736524623.

The spelling of 13561921 in words is "thirteen million, five hundred sixty-one thousand, nine hundred twenty-one".