21709944 has 40 divisors (see below), whose sum is σ = 60809760. Its totient is φ = 7236432.

The previous prime is 21709939. The next prime is 21709949. The reversal of 21709944 is 44990712.

It is an interprime number because it is at equal distance from previous prime (21709939) and next prime (21709949).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21709899 and 21709908.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21709949) 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 in 9 ways as a sum of consecutive naturals, for example, 16104 + ... + 17399.

It is an arithmetic number, because the mean of its divisors is an integer number (1520244).

Almost surely, 2^21709944 is an apocalyptic number.

21709944 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21709944 is an abundant number, since it is smaller than the sum of its proper divisors (39099816).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21709944 is a wasteful number, since it uses less digits than its factorization.

21709944 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33521 (or 33508 counting only the distinct ones).

The product of its (nonzero) digits is 18144, while the sum is 36.

The square root of 21709944 is about 4659.3930935262. The cubic root of 21709944 is about 278.9670443211.

The spelling of 21709944 in words is "twenty-one million, seven hundred nine thousand, nine hundred forty-four".