21409993 has 8 divisors (see below), whose sum is σ = 23412960. Its totient is φ = 19416480.

The previous prime is 21409991. The next prime is 21410003. The reversal of 21409993 is 39990412.

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

It is a cyclic number.

It is not a de Polignac number, because 21409993 - 2¹ = 21409991 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21409991) 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 7 ways as a sum of consecutive naturals, for example, 2898 + ... + 7156.

It is an arithmetic number, because the mean of its divisors is an integer number (2926620).

Almost surely, 2^21409993 is an apocalyptic number.

It is an amenable number.

21409993 is a deficient number, since it is larger than the sum of its proper divisors (2002967).

21409993 is a wasteful number, since it uses less digits than its factorization.

21409993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4727.

The product of its (nonzero) digits is 17496, while the sum is 37.

The square root of 21409993 is about 4627.0933640894. The cubic root of 21409993 is about 277.6763178909.

It can be divided in two parts, 21 and 409993, that added together give a palindrome (410014).

The spelling of 21409993 in words is "twenty-one million, four hundred nine thousand, nine hundred ninety-three".