21403841 has 4 divisors (see below), whose sum is σ = 21436884. Its totient is φ = 21370800.

The previous prime is 21403831. The next prime is 21403849. The reversal of 21403841 is 14830412.

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 15178816 + 6225025 = 3896^2 + 2495^2 .

It is a cyclic number.

It is not a de Polignac number, because 21403841 - 2¹⁰ = 21402817 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21403849) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15530 + ... + 16851.

It is an arithmetic number, because the mean of its divisors is an integer number (5359221).

Almost surely, 2^21403841 is an apocalyptic number.

It is an amenable number.

21403841 is a deficient number, since it is larger than the sum of its proper divisors (33043).

21403841 is an equidigital number, since it uses as much as digits as its factorization.

21403841 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33042.

The product of its (nonzero) digits is 768, while the sum is 23.

The square root of 21403841 is about 4626.4285361389. The cubic root of 21403841 is about 277.6497192779.

The spelling of 21403841 in words is "twenty-one million, four hundred three thousand, eight hundred forty-one".