21869644 has 6 divisors (see below), whose sum is σ = 38271884. Its totient is φ = 10934820.

The previous prime is 21869641. The next prime is 21869669. The reversal of 21869644 is 44696812.

It is a junction number, because it is equal to n+sod(n) for n = 21869597 and 21869606.

It is not an unprimeable number, because it can be changed into a prime (21869641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2733702 + ... + 2733709.

Almost surely, 2^21869644 is an apocalyptic number.

It is an amenable number.

21869644 is a deficient number, since it is larger than the sum of its proper divisors (16402240).

21869644 is a wasteful number, since it uses less digits than its factorization.

21869644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5467415 (or 5467413 counting only the distinct ones).

The product of its digits is 82944, while the sum is 40.

The square root of 21869644 is about 4676.4991179300. The cubic root of 21869644 is about 279.6494081411.

The spelling of 21869644 in words is "twenty-one million, eight hundred sixty-nine thousand, six hundred forty-four".