21158008 has 8 divisors (see below), whose sum is σ = 39671280. Its totient is φ = 10579000.

The previous prime is 21158003. The next prime is 21158041. The reversal of 21158008 is 80085112.

It is a tau number, because it is divible by the number of its divisors (8).

It is a super-2 number, since 2×21158008² = 895322605056128, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21158003) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1322368 + ... + 1322383.

It is an arithmetic number, because the mean of its divisors is an integer number (4958910).

Almost surely, 2^21158008 is an apocalyptic number.

It is an amenable number.

21158008 is a deficient number, since it is larger than the sum of its proper divisors (18513272).

21158008 is a wasteful number, since it uses less digits than its factorization.

21158008 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2644757 (or 2644753 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 25.

The square root of 21158008 is about 4599.7834731648. The cubic root of 21158008 is about 276.5826450880.

The spelling of 21158008 in words is "twenty-one million, one hundred fifty-eight thousand, eight".