21001868 has 12 divisors (see below), whose sum is σ = 38915352. Its totient is φ = 9883200.

The previous prime is 21001867. The next prime is 21001879. The reversal of 21001868 is 86810012.

It is not an unprimeable number, because it can be changed into a prime (21001861) 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, 154358 + ... + 154493.

It is an arithmetic number, because the mean of its divisors is an integer number (3242946).

Almost surely, 2^21001868 is an apocalyptic number.

It is an amenable number.

21001868 is a deficient number, since it is larger than the sum of its proper divisors (17913484).

21001868 is a wasteful number, since it uses less digits than its factorization.

21001868 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 308872 (or 308870 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 26.

The square root of 21001868 is about 4582.7795059331. The cubic root of 21001868 is about 275.9005978247.

The spelling of 21001868 in words is "twenty-one million, one thousand, eight hundred sixty-eight".