21161868 has 48 divisors (see below), whose sum is σ = 60775680. Its totient is φ = 5580864.

The previous prime is 21161867. The next prime is 21161869. The reversal of 21161868 is 86816112.

It is an interprime number because it is at equal distance from previous prime (21161867) and next prime (21161869).

It is not an unprimeable number, because it can be changed into a prime (21161867) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8598 + ... + 10781.

It is an arithmetic number, because the mean of its divisors is an integer number (1266160).

Almost surely, 2^21161868 is an apocalyptic number.

21161868 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21161868 is an abundant number, since it is smaller than the sum of its proper divisors (39613812).

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

21161868 is a wasteful number, since it uses less digits than its factorization.

21161868 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19406 (or 19404 counting only the distinct ones).

The product of its digits is 4608, while the sum is 33.

The square root of 21161868 is about 4600.2030389973. The cubic root of 21161868 is about 276.5994636859.

The spelling of 21161868 in words is "twenty-one million, one hundred sixty-one thousand, eight hundred sixty-eight".