21003948 has 120 divisors (see below), whose sum is σ = 64310960. Its totient is φ = 6001128.

The previous prime is 21003937. The next prime is 21004043. The reversal of 21003948 is 84930012.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 3000561 + ... + 3000567.

Almost surely, 2^21003948 is an apocalyptic number.

21003948 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21003948, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32155480).

21003948 is an abundant number, since it is smaller than the sum of its proper divisors (43307012).

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

21003948 is an frugal number, since it uses more digits than its factorization.

21003948 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53 (or 12 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 21003948 is about 4583.0064368272. The cubic root of 21003948 is about 275.9097058129.

Multiplying 21003948 by its sum of digits (27), we get a square (567106596 = 23814²).

21003948 divided by its sum of digits (27) gives a square (777924 = 882²).

Multiplying 21003948 by its product of nonzero digits (1728), we get a square (36294822144 = 190512²).

The spelling of 21003948 in words is "twenty-one million, three thousand, nine hundred forty-eight".