21329481 has 4 divisors (see below), whose sum is σ = 28439312. Its totient is φ = 14219652.

The previous prime is 21329459. The next prime is 21329489. The reversal of 21329481 is 18492312.

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 not a de Polignac number, because 21329481 - 2⁹ = 21328969 is a prime.

It is a super-2 number, since 2×21329481² = 909893519458722, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21329489) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3554911 + ... + 3554916.

It is an arithmetic number, because the mean of its divisors is an integer number (7109828).

Almost surely, 2^21329481 is an apocalyptic number.

It is an amenable number.

21329481 is a deficient number, since it is larger than the sum of its proper divisors (7109831).

21329481 is an equidigital number, since it uses as much as digits as its factorization.

21329481 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7109830.

The product of its digits is 3456, while the sum is 30.

The square root of 21329481 is about 4618.3851073725. The cubic root of 21329481 is about 277.3278146181.

The spelling of 21329481 in words is "twenty-one million, three hundred twenty-nine thousand, four hundred eighty-one".