21694121 has 4 divisors (see below), whose sum is σ = 21999744. Its totient is φ = 21388500.

The previous prime is 21694069. The next prime is 21694133. The reversal of 21694121 is 12149612.

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 21694121 - 2¹⁰ = 21693097 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21694151) 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, 152705 + ... + 152846.

It is an arithmetic number, because the mean of its divisors is an integer number (5499936).

Almost surely, 2^21694121 is an apocalyptic number.

It is an amenable number.

21694121 is a deficient number, since it is larger than the sum of its proper divisors (305623).

21694121 is an equidigital number, since it uses as much as digits as its factorization.

21694121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 305622.

The product of its digits is 864, while the sum is 26.

The square root of 21694121 is about 4657.6948161081. The cubic root of 21694121 is about 278.8992540593.

The spelling of 21694121 in words is "twenty-one million, six hundred ninety-four thousand, one hundred twenty-one".