21409624385 has 4 divisors (see below), whose sum is σ = 25691549268. Its totient is φ = 17127699504.

The previous prime is 21409624349. The next prime is 21409624387. The reversal of 21409624385 is 58342690412.

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 15688063504 + 5721560881 = 125252^2 + 75641^2 .

It is a cyclic number.

It is not a de Polignac number, because 21409624385 - 2⁶ = 21409624321 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21409624387) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2140962434 + ... + 2140962443.

It is an arithmetic number, because the mean of its divisors is an integer number (6422887317).

Almost surely, 2^21409624385 is an apocalyptic number.

It is an amenable number.

21409624385 is a deficient number, since it is larger than the sum of its proper divisors (4281924883).

21409624385 is an equidigital number, since it uses as much as digits as its factorization.

21409624385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4281924882.

The product of its (nonzero) digits is 414720, while the sum is 44.

The spelling of 21409624385 in words is "twenty-one billion, four hundred nine million, six hundred twenty-four thousand, three hundred eighty-five".