21351187 has 8 divisors (see below), whose sum is σ = 25084080. Its totient is φ = 17916960.

The previous prime is 21351181. The next prime is 21351217. The reversal of 21351187 is 78115312.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21351187 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21351181) 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, 74512 + ... + 74797.

It is an arithmetic number, because the mean of its divisors is an integer number (3135510).

Almost surely, 2^21351187 is an apocalyptic number.

21351187 is a deficient number, since it is larger than the sum of its proper divisors (3732893).

21351187 is a wasteful number, since it uses less digits than its factorization.

21351187 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 149333.

The product of its digits is 1680, while the sum is 28.

The square root of 21351187 is about 4620.7344654286. The cubic root of 21351187 is about 277.4218571738.

Adding to 21351187 its reverse (78115312), we get a palindrome (99466499).

The spelling of 21351187 in words is "twenty-one million, three hundred fifty-one thousand, one hundred eighty-seven".