21550433 has 4 divisors (see below), whose sum is σ = 21562800. Its totient is φ = 21538068.

The previous prime is 21550409. The next prime is 21550447. The reversal of 21550433 is 33405512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21550433 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 = 21550399 and 21550408.

It is not an unprimeable number, because it can be changed into a prime (21550453) 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 3 ways as a sum of consecutive naturals, for example, 3035 + ... + 7232.

It is an arithmetic number, because the mean of its divisors is an integer number (5390700).

Almost surely, 2^21550433 is an apocalyptic number.

It is an amenable number.

21550433 is a deficient number, since it is larger than the sum of its proper divisors (12367).

21550433 is a wasteful number, since it uses less digits than its factorization.

21550433 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12366.

The product of its (nonzero) digits is 1800, while the sum is 23.

The square root of 21550433 is about 4642.2443925326. The cubic root of 21550433 is about 278.2821394205.

Adding to 21550433 its reverse (33405512), we get a palindrome (54955945).

The spelling of 21550433 in words is "twenty-one million, five hundred fifty thousand, four hundred thirty-three".