21033537 has 16 divisors (see below), whose sum is σ = 32504832. Its totient is φ = 11849040.

The previous prime is 21033521. The next prime is 21033541. The reversal of 21033537 is 73533012.

It is not a de Polignac number, because 21033537 - 2⁴ = 21033521 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21033517) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5563 + ... + 8544.

It is an arithmetic number, because the mean of its divisors is an integer number (2031552).

Almost surely, 2^21033537 is an apocalyptic number.

It is an amenable number.

21033537 is a deficient number, since it is larger than the sum of its proper divisors (11471295).

21033537 is a wasteful number, since it uses less digits than its factorization.

21033537 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14188.

The product of its (nonzero) digits is 1890, while the sum is 24.

The square root of 21033537 is about 4586.2334218834. The cubic root of 21033537 is about 276.0392062557.

Adding to 21033537 its reverse (73533012), we get a palindrome (94566549).

The spelling of 21033537 in words is "twenty-one million, thirty-three thousand, five hundred thirty-seven".