21148237 has 4 divisors (see below), whose sum is σ = 23070816. Its totient is φ = 19225660.

The previous prime is 21148223. The next prime is 21148241. The reversal of 21148237 is 73284112.

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 a cyclic number.

It is not a de Polignac number, because 21148237 - 2¹¹ = 21146189 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 (21148207) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 961273 + ... + 961294.

It is an arithmetic number, because the mean of its divisors is an integer number (5767704).

Almost surely, 2^21148237 is an apocalyptic number.

It is an amenable number.

21148237 is a deficient number, since it is larger than the sum of its proper divisors (1922579).

21148237 is a wasteful number, since it uses less digits than its factorization.

21148237 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1922578.

The product of its digits is 2688, while the sum is 28.

The square root of 21148237 is about 4598.7212353001. The cubic root of 21148237 is about 276.5400622332.

The spelling of 21148237 in words is "twenty-one million, one hundred forty-eight thousand, two hundred thirty-seven".