21190237 has 4 divisors (see below), whose sum is σ = 21250620. Its totient is φ = 21129856.

The previous prime is 21190231. The next prime is 21190243. The reversal of 21190237 is 73209112.

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

It is an interprime number because it is at equal distance from previous prime (21190231) and next prime (21190243).

It can be written as a sum of positive squares in 2 ways, for example, as 17214201 + 3976036 = 4149^2 + 1994^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21190237 is a prime.

It is a super-2 number, since 2×21190237² = 898052288232338, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21190231) 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, 29662 + ... + 30367.

It is an arithmetic number, because the mean of its divisors is an integer number (5312655).

Almost surely, 2^21190237 is an apocalyptic number.

It is an amenable number.

21190237 is a deficient number, since it is larger than the sum of its proper divisors (60383).

21190237 is an equidigital number, since it uses as much as digits as its factorization.

21190237 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60382.

The product of its (nonzero) digits is 756, while the sum is 25.

The square root of 21190237 is about 4603.2854571491. The cubic root of 21190237 is about 276.7230089604.

Adding to 21190237 its reverse (73209112), we get a palindrome (94399349).

The spelling of 21190237 in words is "twenty-one million, one hundred ninety thousand, two hundred thirty-seven".