21424661 has 8 divisors (see below), whose sum is σ = 22477824. Its totient is φ = 20381680.

The previous prime is 21424651. The next prime is 21424679. The reversal of 21424661 is 16642412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21424661 - 2¹⁸ = 21162517 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 21424661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21424631) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1955 + ... + 6831.

It is an arithmetic number, because the mean of its divisors is an integer number (2809728).

Almost surely, 2^21424661 is an apocalyptic number.

It is an amenable number.

21424661 is a deficient number, since it is larger than the sum of its proper divisors (1053163).

21424661 is a wasteful number, since it uses less digits than its factorization.

21424661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5091.

The product of its digits is 2304, while the sum is 26.

The square root of 21424661 is about 4628.6781050317. The cubic root of 21424661 is about 277.7397154900.

The spelling of 21424661 in words is "twenty-one million, four hundred twenty-four thousand, six hundred sixty-one".