21253037 has 4 divisors (see below), whose sum is σ = 22887900. Its totient is φ = 19618176.

The previous prime is 21253033. The next prime is 21253093. The reversal of 21253037 is 73035212.

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 7070281 + 14182756 = 2659^2 + 3766^2 .

It is a cyclic number.

It is not a de Polignac number, because 21253037 - 2² = 21253033 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 (21253033) 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, 817412 + ... + 817437.

It is an arithmetic number, because the mean of its divisors is an integer number (5721975).

Almost surely, 2^21253037 is an apocalyptic number.

It is an amenable number.

21253037 is a deficient number, since it is larger than the sum of its proper divisors (1634863).

21253037 is a wasteful number, since it uses less digits than its factorization.

21253037 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1634862.

The product of its (nonzero) digits is 1260, while the sum is 23.

The square root of 21253037 is about 4610.1016257779. The cubic root of 21253037 is about 276.9961074579.

Adding to 21253037 its reverse (73035212), we get a palindrome (94288249).

The spelling of 21253037 in words is "twenty-one million, two hundred fifty-three thousand, thirty-seven".