21145337 has 4 divisors (see below), whose sum is σ = 21154980. Its totient is φ = 21135696.

The previous prime is 21145307. The next prime is 21145343. The reversal of 21145337 is 73354112.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 15594601 + 5550736 = 3949^2 + 2356^2 .

It is a cyclic number.

It is not a de Polignac number, because 21145337 - 2¹⁶ = 21079801 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21145307) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 239 + ... + 6507.

It is an arithmetic number, because the mean of its divisors is an integer number (5288745).

Almost surely, 2^21145337 is an apocalyptic number.

It is an amenable number.

21145337 is a deficient number, since it is larger than the sum of its proper divisors (9643).

21145337 is an equidigital number, since it uses as much as digits as its factorization.

21145337 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9642.

The product of its digits is 2520, while the sum is 26.

The square root of 21145337 is about 4598.4059194464. The cubic root of 21145337 is about 276.5274212608.

Adding to 21145337 its reverse (73354112), we get a palindrome (94499449).

The spelling of 21145337 in words is "twenty-one million, one hundred forty-five thousand, three hundred thirty-seven".