21231087 has 8 divisors (see below), whose sum is σ = 28427520. Its totient is φ = 14094360.

The previous prime is 21231029. The next prime is 21231107. The reversal of 21231087 is 78013212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21231087 - 2⁷ = 21230959 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21231787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14089 + ... + 15522.

It is an arithmetic number, because the mean of its divisors is an integer number (3553440).

Almost surely, 2^21231087 is an apocalyptic number.

21231087 is a deficient number, since it is larger than the sum of its proper divisors (7196433).

21231087 is a wasteful number, since it uses less digits than its factorization.

21231087 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29853.

The product of its (nonzero) digits is 672, while the sum is 24.

The square root of 21231087 is about 4607.7203691196. The cubic root of 21231087 is about 276.9007146769.

Adding to 21231087 its reverse (78013212), we get a palindrome (99244299).

The spelling of 21231087 in words is "twenty-one million, two hundred thirty-one thousand, eighty-seven".