21865036 has 6 divisors (see below), whose sum is σ = 38263820. Its totient is φ = 10932516.

The previous prime is 21865007. The next prime is 21865037. The reversal of 21865036 is 63056812.

It is a junction number, because it is equal to n+sod(n) for n = 21864989 and 21865007.

It is not an unprimeable number, because it can be changed into a prime (21865037) 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 as a sum of consecutive naturals, namely, 2733126 + ... + 2733133.

Almost surely, 2^21865036 is an apocalyptic number.

It is an amenable number.

21865036 is a deficient number, since it is larger than the sum of its proper divisors (16398784).

21865036 is a wasteful number, since it uses less digits than its factorization.

21865036 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5466263 (or 5466261 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 31.

The square root of 21865036 is about 4676.0064157355. The cubic root of 21865036 is about 279.6297657700.

The spelling of 21865036 in words is "twenty-one million, eight hundred sixty-five thousand, thirty-six".