21158144 has 36 divisors (see below), whose sum is σ = 48271104. Its totient is φ = 9067008.

The previous prime is 21158141. The next prime is 21158147. The reversal of 21158144 is 44185112.

It is an interprime number because it is at equal distance from previous prime (21158141) and next prime (21158147).

It is a hoax number, since the sum of its digits (26) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21158141) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4112 + ... + 7695.

It is an arithmetic number, because the mean of its divisors is an integer number (1340864).

Almost surely, 2^21158144 is an apocalyptic number.

It is an amenable number.

21158144 is an abundant number, since it is smaller than the sum of its proper divisors (27112960).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21158144 is an equidigital number, since it uses as much as digits as its factorization.

21158144 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11830 (or 11816 counting only the distinct ones).

The product of its digits is 1280, while the sum is 26.

The square root of 21158144 is about 4599.7982564456. The cubic root of 21158144 is about 276.5832376951.

The spelling of 21158144 in words is "twenty-one million, one hundred fifty-eight thousand, one hundred forty-four".