21212587 has 8 divisors (see below), whose sum is σ = 23887872. Its totient is φ = 18661800.

The previous prime is 21212537. The next prime is 21212591. The reversal of 21212587 is 78521212.

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 21212587 - 2¹⁵ = 21179819 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21212537) 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, 30763 + ... + 31444.

It is an arithmetic number, because the mean of its divisors is an integer number (2985984).

Almost surely, 2^21212587 is an apocalyptic number.

21212587 is a deficient number, since it is larger than the sum of its proper divisors (2675285).

21212587 is a wasteful number, since it uses less digits than its factorization.

21212587 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 62249.

The product of its digits is 2240, while the sum is 28.

The square root of 21212587 is about 4605.7124313183. The cubic root of 21212587 is about 276.8202642217.

Adding to 21212587 its reverse (78521212), we get a palindrome (99733799).

It can be divided in two parts, 212125 and 87, that added together give a palindrome (212212).

The spelling of 21212587 in words is "twenty-one million, two hundred twelve thousand, five hundred eighty-seven".