21350021 has 8 divisors (see below), whose sum is σ = 26618304. Its totient is φ = 16636320.

The previous prime is 21350009. The next prime is 21350027. The reversal of 21350021 is 12005312.

It is a happy number.

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 21350021 - 2¹⁰ = 21348997 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21349978 and 21350005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21350027) 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, 138560 + ... + 138713.

It is an arithmetic number, because the mean of its divisors is an integer number (3327288).

Almost surely, 2^21350021 is an apocalyptic number.

It is an amenable number.

21350021 is a deficient number, since it is larger than the sum of its proper divisors (5268283).

21350021 is a wasteful number, since it uses less digits than its factorization.

21350021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 277291.

The product of its (nonzero) digits is 60, while the sum is 14.

The square root of 21350021 is about 4620.6082932878. The cubic root of 21350021 is about 277.4168070288.

Adding to 21350021 its reverse (12005312), we get a palindrome (33355333).

The spelling of 21350021 in words is "twenty-one million, three hundred fifty thousand, twenty-one".