21213053 has 4 divisors (see below), whose sum is σ = 21226908. Its totient is φ = 21199200.

The previous prime is 21213047. The next prime is 21213089. The reversal of 21213053 is 35031212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12201049 + 9012004 = 3493^2 + 3002^2 .

It is a cyclic number.

It is not a de Polignac number, because 21213053 - 2¹⁶ = 21147517 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21213013) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4298 + ... + 7803.

It is an arithmetic number, because the mean of its divisors is an integer number (5306727).

Almost surely, 2^21213053 is an apocalyptic number.

It is an amenable number.

21213053 is a deficient number, since it is larger than the sum of its proper divisors (13855).

21213053 is a wasteful number, since it uses less digits than its factorization.

21213053 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13854.

The product of its (nonzero) digits is 180, while the sum is 17.

The square root of 21213053 is about 4605.7630203909. The cubic root of 21213053 is about 276.8222912776.

Adding to 21213053 its reverse (35031212), we get a palindrome (56244265).

The spelling of 21213053 in words is "twenty-one million, two hundred thirteen thousand, fifty-three".