21231587 has 8 divisors (see below), whose sum is σ = 22910496. Its totient is φ = 19559232.

The previous prime is 21231583. The next prime is 21231601. The reversal of 21231587 is 78513212.

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

It is a cyclic number.

It is not a de Polignac number, because 21231587 - 2² = 21231583 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21231583) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6698 + ... + 9344.

It is an arithmetic number, because the mean of its divisors is an integer number (2863812).

Almost surely, 2^21231587 is an apocalyptic number.

21231587 is a deficient number, since it is larger than the sum of its proper divisors (1678909).

21231587 is a wasteful number, since it uses less digits than its factorization.

21231587 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3277.

The product of its digits is 3360, while the sum is 29.

The square root of 21231587 is about 4607.7746255649. The cubic root of 21231587 is about 276.9028883648.

Adding to 21231587 its reverse (78513212), we get a palindrome (99744799).

The spelling of 21231587 in words is "twenty-one million, two hundred thirty-one thousand, five hundred eighty-seven".