21457233 has 12 divisors (see below), whose sum is σ = 35421568. Its totient is φ = 12261240.

The previous prime is 21457207. The next prime is 21457253. The reversal of 21457233 is 33275412.

It is not a de Polignac number, because 21457233 - 2⁵ = 21457201 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21457197 and 21457206.

It is not an unprimeable number, because it can be changed into a prime (21457253) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 170233 + ... + 170358.

Almost surely, 2^21457233 is an apocalyptic number.

It is an amenable number.

21457233 is a deficient number, since it is larger than the sum of its proper divisors (13964335).

21457233 is a wasteful number, since it uses less digits than its factorization.

21457233 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 340604 (or 340601 counting only the distinct ones).

The product of its digits is 5040, while the sum is 27.

The square root of 21457233 is about 4632.1952679048. The cubic root of 21457233 is about 277.8803938323.

The spelling of 21457233 in words is "twenty-one million, four hundred fifty-seven thousand, two hundred thirty-three".