21148231 has 16 divisors (see below), whose sum is σ = 23795968. Its totient is φ = 18662400.

The previous prime is 21148223. The next prime is 21148241. The reversal of 21148231 is 13284112.

It is a happy number.

It is a 10-Lehmer number, since φ(21148231) divides (21148231-1)¹⁰.

It is a cyclic number.

It is not a de Polignac number, because 21148231 - 2³ = 21148223 is a prime.

It is a super-2 number, since 2×21148231² = 894495348858722, 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 (21148241) 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 15 ways as a sum of consecutive naturals, for example, 38821 + ... + 39361.

It is an arithmetic number, because the mean of its divisors is an integer number (1487248).

Almost surely, 2^21148231 is an apocalyptic number.

21148231 is a deficient number, since it is larger than the sum of its proper divisors (2647737).

21148231 is a wasteful number, since it uses less digits than its factorization.

21148231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 682.

The product of its digits is 384, while the sum is 22.

The square root of 21148231 is about 4598.7205829448. The cubic root of 21148231 is about 276.5400360806.

The spelling of 21148231 in words is "twenty-one million, one hundred forty-eight thousand, two hundred thirty-one".