21511053 has 6 divisors (see below), whose sum is σ = 31071534. Its totient is φ = 14340696.

The previous prime is 21511031. The next prime is 21511079. The reversal of 21511053 is 35011512.

It can be written as a sum of positive squares in only one way, i.e., 21511044 + 9 = 4638^2 + 3^2 .

It is not a de Polignac number, because 21511053 - 2¹⁰ = 21510029 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21511013) 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, 1195050 + ... + 1195067.

It is an arithmetic number, because the mean of its divisors is an integer number (5178589).

Almost surely, 2^21511053 is an apocalyptic number.

It is an amenable number.

21511053 is a deficient number, since it is larger than the sum of its proper divisors (9560481).

21511053 is a wasteful number, since it uses less digits than its factorization.

21511053 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2390123 (or 2390120 counting only the distinct ones).

The product of its (nonzero) digits is 150, while the sum is 18.

The square root of 21511053 is about 4638.0009702457. Note that the first 3 decimals coincide. The cubic root of 21511053 is about 278.1125305692.

Adding to 21511053 its reverse (35011512), we get a palindrome (56522565).

The spelling of 21511053 in words is "twenty-one million, five hundred eleven thousand, fifty-three".