21212752 has 30 divisors (see below), whose sum is σ = 45179834. Its totient is φ = 9641280.

The previous prime is 21212749. The next prime is 21212777. The reversal of 21212752 is 25721212.

It can be written as a sum of positive squares in only one way, i.e., 18974736 + 2238016 = 4356^2 + 1496^2 .

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a congruent number.

It is an unprimeable number.

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, 3543 + ... + 7414.

Almost surely, 2^21212752 is an apocalyptic number.

21212752 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21212752 is an abundant number, since it is smaller than the sum of its proper divisors (23967082).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21212752 is a wasteful number, since it uses less digits than its factorization.

21212752 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10987 (or 10970 counting only the distinct ones).

The product of its digits is 560, while the sum is 22.

The square root of 21212752 is about 4605.7303438217. The cubic root of 21212752 is about 276.8209819594.

Adding to 21212752 its reverse (25721212), we get a palindrome (46933964).

The spelling of 21212752 in words is "twenty-one million, two hundred twelve thousand, seven hundred fifty-two".