21383748 has 18 divisors (see below), whose sum is σ = 54053454. Its totient is φ = 7127904.

The previous prime is 21383723. The next prime is 21383749. The reversal of 21383748 is 84738312.

It can be written as a sum of positive squares in only one way, i.e., 19079424 + 2304324 = 4368^2 + 1518^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 593993 = 21383748 / (2 + 1 + 3 + 8 + 3 + 7 + 4 + 8).

It is not an unprimeable number, because it can be changed into a prime (21383749) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 296961 + ... + 297032.

Almost surely, 2^21383748 is an apocalyptic number.

It is an amenable number.

21383748 is an abundant number, since it is smaller than the sum of its proper divisors (32669706).

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

21383748 is a wasteful number, since it uses less digits than its factorization.

21383748 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 594003 (or 593998 counting only the distinct ones).

The product of its digits is 32256, while the sum is 36.

The square root of 21383748 is about 4624.2564807761. The cubic root of 21383748 is about 277.5628102283.

It can be divided in two parts, 2138 and 3748, that added together give a triangular number (5886 = T₁₀₈).

The spelling of 21383748 in words is "twenty-one million, three hundred eighty-three thousand, seven hundred forty-eight".