21149748 has 42 divisors (see below), whose sum is σ = 55500354. Its totient is φ = 7048944.

The previous prime is 21149747. The next prime is 21149761. The reversal of 21149748 is 84794112.

It can be written as a sum of positive squares in only one way, i.e., 19607184 + 1542564 = 4428^2 + 1242^2 .

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21149741) by changing a digit.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 711 + ... + 6542.

It is an arithmetic number, because the mean of its divisors is an integer number (1321437).

Almost surely, 2^21149748 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21149748, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27750177).

21149748 is an abundant number, since it is smaller than the sum of its proper divisors (34350606).

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

21149748 is an equidigital number, since it uses as much as digits as its factorization.

21149748 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7275 (or 7258 counting only the distinct ones).

The product of its digits is 16128, while the sum is 36.

The square root of 21149748 is about 4598.8855171661. The cubic root of 21149748 is about 276.5466481578.

It can be divided in two parts, 21 and 149748, that added together give a square (149769 = 387²).

The spelling of 21149748 in words is "twenty-one million, one hundred forty-nine thousand, seven hundred forty-eight".