21684041 has 4 divisors (see below), whose sum is σ = 21734784. Its totient is φ = 21633300.

The previous prime is 21684031. The next prime is 21684043. The reversal of 21684041 is 14048612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21684041 - 2¹⁰ = 21683017 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 21684041.

It is not an unprimeable number, because it can be changed into a prime (21684043) 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, 24725 + ... + 25586.

It is an arithmetic number, because the mean of its divisors is an integer number (5433696).

Almost surely, 2^21684041 is an apocalyptic number.

It is an amenable number.

21684041 is a deficient number, since it is larger than the sum of its proper divisors (50743).

21684041 is an equidigital number, since it uses as much as digits as its factorization.

21684041 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50742.

The product of its (nonzero) digits is 1536, while the sum is 26.

The square root of 21684041 is about 4656.6126100418. The cubic root of 21684041 is about 278.8560512639.

The spelling of 21684041 in words is "twenty-one million, six hundred eighty-four thousand, forty-one".