21820124 has 12 divisors (see below), whose sum is σ = 38486784. Its totient is φ = 10823904.

The previous prime is 21820111. The next prime is 21820133. The reversal of 21820124 is 42102812.

It is a happy number.

It is a super-2 number, since 2×21820124² = 952235622750752, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21820096 and 21820105.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20969 + ... + 21984.

It is an arithmetic number, because the mean of its divisors is an integer number (3207232).

Almost surely, 2^21820124 is an apocalyptic number.

It is an amenable number.

21820124 is a deficient number, since it is larger than the sum of its proper divisors (16666660).

21820124 is a wasteful number, since it uses less digits than its factorization.

21820124 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43084 (or 43082 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 20.

The square root of 21820124 is about 4671.2015584858. The cubic root of 21820124 is about 279.4381761679.

Adding to 21820124 its reverse (42102812), we get a palindrome (63922936).

The spelling of 21820124 in words is "twenty-one million, eight hundred twenty thousand, one hundred twenty-four".