21158187 has 8 divisors (see below), whose sum is σ = 28490640. Its totient is φ = 13965600.

The previous prime is 21158177. The next prime is 21158201. The reversal of 21158187 is 78185112.

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

It is not a de Polignac number, because 21158187 - 2¹⁴ = 21141803 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21158147) 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, 34612 + ... + 35217.

It is an arithmetic number, because the mean of its divisors is an integer number (3561330).

Almost surely, 2^21158187 is an apocalyptic number.

21158187 is a deficient number, since it is larger than the sum of its proper divisors (7332453).

21158187 is a wasteful number, since it uses less digits than its factorization.

21158187 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69933.

The product of its digits is 4480, while the sum is 33.

The square root of 21158187 is about 4599.8029305613. The cubic root of 21158187 is about 276.5834250630.

The spelling of 21158187 in words is "twenty-one million, one hundred fifty-eight thousand, one hundred eighty-seven".