21639348 has 18 divisors (see below), whose sum is σ = 54699554. Its totient is φ = 7213104.

The previous prime is 21639341. The next prime is 21639361. The reversal of 21639348 is 84393612.

It can be written as a sum of positive squares in only one way, i.e., 20903184 + 736164 = 4572^2 + 858^2 .

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

It is a super-2 number, since 2×21639348² = 936522763730208, which contains 22 as substring.

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: 601093 = 21639348 / (2 + 1 + 6 + 3 + 9 + 3 + 4 + 8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21639341) 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, 300511 + ... + 300582.

Almost surely, 2^21639348 is an apocalyptic number.

It is an amenable number.

21639348 is an abundant number, since it is smaller than the sum of its proper divisors (33060206).

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

21639348 is a wasteful number, since it uses less digits than its factorization.

21639348 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 601103 (or 601098 counting only the distinct ones).

The product of its digits is 31104, while the sum is 36.

The square root of 21639348 is about 4651.8112601437. The cubic root of 21639348 is about 278.6643359873.

It can be divided in two parts, 2163 and 9348, that added together give a palindrome (11511).

The spelling of 21639348 in words is "twenty-one million, six hundred thirty-nine thousand, three hundred forty-eight".