21859144 has 32 divisors (see below), whose sum is σ = 43870680. Its totient is φ = 10174464.

The previous prime is 21859141. The next prime is 21859147. The reversal of 21859144 is 44195812.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21859141) and next prime (21859147).

It can be written as a sum of positive squares in 4 ways, for example, as 19096900 + 2762244 = 4370^2 + 1662^2 .

It is a Harshad number since it is a multiple of its sum of digits (34).

It is not an unprimeable number, because it can be changed into a prime (21859141) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 12364 + ... + 14020.

Almost surely, 2^21859144 is an apocalyptic number.

It is an amenable number.

21859144 is an abundant number, since it is smaller than the sum of its proper divisors (22011536).

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

21859144 is a wasteful number, since it uses less digits than its factorization.

21859144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1777 (or 1773 counting only the distinct ones).

The product of its digits is 11520, while the sum is 34.

The square root of 21859144 is about 4675.3763484879. The cubic root of 21859144 is about 279.6046461133.

The spelling of 21859144 in words is "twenty-one million, eight hundred fifty-nine thousand, one hundred forty-four".