21859408 has 10 divisors (see below), whose sum is σ = 42352634. Its totient is φ = 10929696.

The previous prime is 21859403. The next prime is 21859421. The reversal of 21859408 is 80495812.

It can be written as a sum of positive squares in only one way, i.e., 12446784 + 9412624 = 3528^2 + 3068^2 .

It is a super-2 number, since 2×21859408² = 955667436220928, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21859403) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 683091 + ... + 683122.

Almost surely, 2^21859408 is an apocalyptic number.

It is an amenable number.

21859408 is a deficient number, since it is larger than the sum of its proper divisors (20493226).

21859408 is a wasteful number, since it uses less digits than its factorization.

21859408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1366221 (or 1366215 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 37.

The square root of 21859408 is about 4675.4045814239. The cubic root of 21859408 is about 279.6057717342.

The spelling of 21859408 in words is "twenty-one million, eight hundred fifty-nine thousand, four hundred eight".