21234891 has 8 divisors (see below), whose sum is σ = 28517440. Its totient is φ = 14054472.

The previous prime is 21234877. The next prime is 21234923. The reversal of 21234891 is 19843212.

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

It is not a de Polignac number, because 21234891 - 2⁹ = 21234379 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21234841) 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, 25045 + ... + 25878.

It is an arithmetic number, because the mean of its divisors is an integer number (3564680).

Almost surely, 2^21234891 is an apocalyptic number.

21234891 is a deficient number, since it is larger than the sum of its proper divisors (7282549).

21234891 is a wasteful number, since it uses less digits than its factorization.

21234891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51065.

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

The square root of 21234891 is about 4608.1331360975. The cubic root of 21234891 is about 276.9172512367.

The spelling of 21234891 in words is "twenty-one million, two hundred thirty-four thousand, eight hundred ninety-one".