21421331 has 8 divisors (see below), whose sum is σ = 21980160. Its totient is φ = 20866888.

The previous prime is 21421319. The next prime is 21421333. The reversal of 21421331 is 13312412.

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 21421331 - 2²² = 17227027 is a prime.

It is a super-2 number, since 2×21421331² = 917746843623122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21421333) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10280 + ... + 12186.

It is an arithmetic number, because the mean of its divisors is an integer number (2747520).

Almost surely, 2^21421331 is an apocalyptic number.

21421331 is a deficient number, since it is larger than the sum of its proper divisors (558829).

21421331 is a wasteful number, since it uses less digits than its factorization.

21421331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2193.

The product of its digits is 144, while the sum is 17.

The square root of 21421331 is about 4628.3183771214. The cubic root of 21421331 is about 277.7253252012.

Adding to 21421331 its reverse (13312412), we get a palindrome (34733743).

The spelling of 21421331 in words is "twenty-one million, four hundred twenty-one thousand, three hundred thirty-one".