21212153 has 6 divisors (see below), whose sum is σ = 21919482. Its totient is φ = 20526960.

The previous prime is 21212143. The next prime is 21212159. The reversal of 21212153 is 35121212.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 21049744 + 162409 = 4588^2 + 403^2 .

It is not a de Polignac number, because 21212153 - 2⁶ = 21212089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21212159) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 10076 + ... + 11997.

It is an arithmetic number, because the mean of its divisors is an integer number (3653247).

Almost surely, 2^21212153 is an apocalyptic number.

It is an amenable number.

21212153 is a deficient number, since it is larger than the sum of its proper divisors (707329).

21212153 is an equidigital number, since it uses as much as digits as its factorization.

21212153 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22135 (or 22104 counting only the distinct ones).

The product of its digits is 120, while the sum is 17.

The square root of 21212153 is about 4605.6653156737. The cubic root of 21212153 is about 276.8183763360.

Adding to 21212153 its reverse (35121212), we get a palindrome (56333365).

The spelling of 21212153 in words is "twenty-one million, two hundred twelve thousand, one hundred fifty-three".