21237897 has 4 divisors (see below), whose sum is σ = 28317200. Its totient is φ = 14158596.

The previous prime is 21237847. The next prime is 21237899. The reversal of 21237897 is 79873212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21237897 - 2¹¹ = 21235849 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21237899) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3539647 + ... + 3539652.

It is an arithmetic number, because the mean of its divisors is an integer number (7079300).

Almost surely, 2^21237897 is an apocalyptic number.

It is an amenable number.

21237897 is a deficient number, since it is larger than the sum of its proper divisors (7079303).

21237897 is an equidigital number, since it uses as much as digits as its factorization.

21237897 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7079302.

The product of its digits is 42336, while the sum is 39.

The square root of 21237897 is about 4608.4592870069. The cubic root of 21237897 is about 276.9303173736.

The spelling of 21237897 in words is "twenty-one million, two hundred thirty-seven thousand, eight hundred ninety-seven".