21921104 has 10 divisors (see below), whose sum is σ = 42472170. Its totient is φ = 10960544.

The previous prime is 21921083. The next prime is 21921113. The reversal of 21921104 is 40112912.

It can be written as a sum of positive squares in only one way, i.e., 18079504 + 3841600 = 4252^2 + 1960^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 685019 + ... + 685050.

It is an arithmetic number, because the mean of its divisors is an integer number (4247217).

Almost surely, 2^21921104 is an apocalyptic number.

It is an amenable number.

21921104 is a deficient number, since it is larger than the sum of its proper divisors (20551066).

21921104 is a wasteful number, since it uses less digits than its factorization.

21921104 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1370077 (or 1370071 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 20.

The square root of 21921104 is about 4681.9978641601. The cubic root of 21921104 is about 279.8685777804.

Adding to 21921104 its sum of digits (20), we get a square (21921124 = 4682²).

The spelling of 21921104 in words is "twenty-one million, nine hundred twenty-one thousand, one hundred four".