21234991 has 8 divisors (see below), whose sum is σ = 21802880. Its totient is φ = 20670552.

The previous prime is 21234973. The next prime is 21235001. The reversal of 21234991 is 19943212.

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 21234991 - 2¹¹ = 21232943 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21234091) 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, 15646 + ... + 16948.

It is an arithmetic number, because the mean of its divisors is an integer number (2725360).

Almost surely, 2^21234991 is an apocalyptic number.

21234991 is a deficient number, since it is larger than the sum of its proper divisors (567889).

21234991 is a wasteful number, since it uses less digits than its factorization.

21234991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1725.

The product of its digits is 3888, while the sum is 31.

The square root of 21234991 is about 4608.1439864657. The cubic root of 21234991 is about 276.9176859250.

The spelling of 21234991 in words is "twenty-one million, two hundred thirty-four thousand, nine hundred ninety-one".