21212373 has 48 divisors (see below), whose sum is σ = 36072960. Its totient is φ = 10850112.

The previous prime is 21212353. The next prime is 21212423. The reversal of 21212373 is 37321212.

It is not a de Polignac number, because 21212373 - 2¹⁴ = 21195989 is a prime.

It is a super-2 number, since 2×21212373² = 899929536582258, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212353) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 152538 + ... + 152676.

It is an arithmetic number, because the mean of its divisors is an integer number (751520).

Almost surely, 2^21212373 is an apocalyptic number.

It is an amenable number.

21212373 is a deficient number, since it is larger than the sum of its proper divisors (14860587).

21212373 is a wasteful number, since it uses less digits than its factorization.

21212373 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 218 (or 205 counting only the distinct ones).

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

The square root of 21212373 is about 4605.6891992404. The cubic root of 21212373 is about 276.8193333320.

Adding to 21212373 its reverse (37321212), we get a palindrome (58533585).

The spelling of 21212373 in words is "twenty-one million, two hundred twelve thousand, three hundred seventy-three".