21257433 has 6 divisors (see below), whose sum is σ = 30705194. Its totient is φ = 14171616.

The previous prime is 21257419. The next prime is 21257461. The reversal of 21257433 is 33475212.

It can be written as a sum of positive squares in only one way, i.e., 14538969 + 6718464 = 3813^2 + 2592^2 .

It is not a de Polignac number, because 21257433 - 2⁴ = 21257417 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21257397 and 21257406.

It is not an unprimeable number, because it can be changed into a prime (21257473) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1180960 + ... + 1180977.

Almost surely, 2^21257433 is an apocalyptic number.

It is an amenable number.

21257433 is a deficient number, since it is larger than the sum of its proper divisors (9447761).

21257433 is a wasteful number, since it uses less digits than its factorization.

21257433 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2361943 (or 2361940 counting only the distinct ones).

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

The square root of 21257433 is about 4610.5783802035. The cubic root of 21257433 is about 277.0152041944.

The spelling of 21257433 in words is "twenty-one million, two hundred fifty-seven thousand, four hundred thirty-three".