21865960 has 32 divisors (see below), whose sum is σ = 51789600. Its totient is φ = 8285760.

The previous prime is 21865957. The next prime is 21865967. The reversal of 21865960 is 6956812.

It is not an unprimeable number, because it can be changed into a prime (21865967) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13626 + ... + 15145.

It is an arithmetic number, because the mean of its divisors is an integer number (1618425).

Almost surely, 2^21865960 is an apocalyptic number.

21865960 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21865960 is an abundant number, since it is smaller than the sum of its proper divisors (29923640).

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

21865960 is a wasteful number, since it uses less digits than its factorization.

21865960 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28801 (or 28797 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 37.

The square root of 21865960 is about 4676.1052169514. The cubic root of 21865960 is about 279.6337046958.

The spelling of 21865960 in words is "twenty-one million, eight hundred sixty-five thousand, nine hundred sixty".