21017944 has 8 divisors (see below), whose sum is σ = 39408660. Its totient is φ = 10508968.

The previous prime is 21017897. The next prime is 21017951. The reversal of 21017944 is 44971012.

It is a tau number, because it is divible by the number of its divisors (8).

It is a hoax number, since the sum of its digits (28) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1313614 + ... + 1313629.

Almost surely, 2^21017944 is an apocalyptic number.

It is an amenable number.

21017944 is a deficient number, since it is larger than the sum of its proper divisors (18390716).

21017944 is a wasteful number, since it uses less digits than its factorization.

21017944 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2627249 (or 2627245 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 28.

The square root of 21017944 is about 4584.5331278114. The cubic root of 21017944 is about 275.9709764342.

Adding to 21017944 its reverse (44971012), we get a palindrome (65988956).

The spelling of 21017944 in words is "twenty-one million, seventeen thousand, nine hundred forty-four".