21161668 has 48 divisors (see below), whose sum is σ = 45057600. Its totient is φ = 8570880.

The previous prime is 21161653. The next prime is 21161671. The reversal of 21161668 is 86616112.

It is an unprimeable number.

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 in 15 ways as a sum of consecutive naturals, for example, 13468 + ... + 14956.

It is an arithmetic number, because the mean of its divisors is an integer number (938700).

Almost surely, 2^21161668 is an apocalyptic number.

It is an amenable number.

21161668 is an abundant number, since it is smaller than the sum of its proper divisors (23895932).

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

21161668 is a wasteful number, since it uses less digits than its factorization.

21161668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1540 (or 1538 counting only the distinct ones).

The product of its digits is 3456, while the sum is 31.

The square root of 21161668 is about 4600.1813007750. The cubic root of 21161668 is about 276.5985923062.

The spelling of 21161668 in words is "twenty-one million, one hundred sixty-one thousand, six hundred sixty-eight".