21698644 has 24 divisors (see below), whose sum is σ = 41686848. Its totient is φ = 9800640.

The previous prime is 21698639. The next prime is 21698657. The reversal of 21698644 is 44689612.

It is a junction number, because it is equal to n+sod(n) for n = 21698597 and 21698606.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5872 + ... + 8824.

It is an arithmetic number, because the mean of its divisors is an integer number (1736952).

Almost surely, 2^21698644 is an apocalyptic number.

It is an amenable number.

21698644 is a deficient number, since it is larger than the sum of its proper divisors (19988204).

21698644 is a wasteful number, since it uses less digits than its factorization.

21698644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3135 (or 3133 counting only the distinct ones).

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

The square root of 21698644 is about 4658.1803314170. The cubic root of 21698644 is about 278.9186352497.

The spelling of 21698644 in words is "twenty-one million, six hundred ninety-eight thousand, six hundred forty-four".