21256433 has 6 divisors (see below), whose sum is σ = 23364642. Its totient is φ = 19323920.

The previous prime is 21256399. The next prime is 21256447. The reversal of 21256433 is 33465212.

It can be written as a sum of positive squares in only one way, i.e., 20539024 + 717409 = 4532^2 + 847^2 .

It is not a de Polignac number, because 21256433 - 2⁶ = 21256369 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21256033) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 87716 + ... + 87957.

It is an arithmetic number, because the mean of its divisors is an integer number (3894107).

Almost surely, 2^21256433 is an apocalyptic number.

It is an amenable number.

21256433 is a deficient number, since it is larger than the sum of its proper divisors (2108209).

21256433 is a wasteful number, since it uses less digits than its factorization.

21256433 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 175695 (or 175684 counting only the distinct ones).

The product of its digits is 4320, while the sum is 26.

The square root of 21256433 is about 4610.4699326641. The cubic root of 21256433 is about 277.0108603092.

It can be divided in two parts, 2125 and 6433, that added together give a palindrome (8558).

The spelling of 21256433 in words is "twenty-one million, two hundred fifty-six thousand, four hundred thirty-three".