21172233 has 16 divisors (see below), whose sum is σ = 29401920. Its totient is φ = 13535424.

The previous prime is 21172223. The next prime is 21172241. The reversal of 21172233 is 33227112.

It is not a de Polignac number, because 21172233 - 2¹² = 21168137 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21172223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13435 + ... + 14927.

It is an arithmetic number, because the mean of its divisors is an integer number (1837620).

Almost surely, 2^21172233 is an apocalyptic number.

It is an amenable number.

21172233 is a deficient number, since it is larger than the sum of its proper divisors (8229687).

21172233 is a wasteful number, since it uses less digits than its factorization.

21172233 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1688.

The product of its digits is 504, while the sum is 21.

The square root of 21172233 is about 4601.3294817911. The cubic root of 21172233 is about 276.6446154261.

Adding to 21172233 its reverse (33227112), we get a palindrome (54399345).

The spelling of 21172233 in words is "twenty-one million, one hundred seventy-two thousand, two hundred thirty-three".