21859960 has 96 divisors (see below), whose sum is σ = 54817920. Its totient is φ = 7833600.

The previous prime is 21859949. The next prime is 21859973. The reversal of 21859960 is 6995812.

21859960 = T₃₈₁₆ + T₃₈₁₇ + T₃₈₁₈.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a congruent number.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 358330 + ... + 358390.

It is an arithmetic number, because the mean of its divisors is an integer number (571020).

Almost surely, 2^21859960 is an apocalyptic number.

21859960 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

21859960 is the 3818-th centered triangular number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21859960, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27408960).

21859960 is an abundant number, since it is smaller than the sum of its proper divisors (32957960).

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

21859960 is a wasteful number, since it uses less digits than its factorization.

21859960 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 137 (or 116 counting only the distinct ones).

The product of its (nonzero) digits is 38880, while the sum is 40.

The square root of 21859960 is about 4675.4636133757. The cubic root of 21859960 is about 279.6081252760.

The spelling of 21859960 in words is "twenty-one million, eight hundred fifty-nine thousand, nine hundred sixty".