21305076 has 48 divisors (see below), whose sum is σ = 54858048. Its totient is φ = 6393600.

The previous prime is 21305071. The next prime is 21305101. The reversal of 21305076 is 67050312.

It is a hoax number, since the sum of its digits (24) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21305071) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4731 + ... + 8061.

It is an arithmetic number, because the mean of its divisors is an integer number (1142876).

Almost surely, 2^21305076 is an apocalyptic number.

21305076 is a gapful number since it is divisible by the number (26) 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 21305076, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27429024).

21305076 is an abundant number, since it is smaller than the sum of its proper divisors (33552972).

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

21305076 is a wasteful number, since it uses less digits than its factorization.

21305076 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3392 (or 3390 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 24.

The square root of 21305076 is about 4615.7421938406. The cubic root of 21305076 is about 277.2220022557. Note that the first 3 decimals are identical.

Adding to 21305076 its reverse (67050312), we get a palindrome (88355388).

The spelling of 21305076 in words is "twenty-one million, three hundred five thousand, seventy-six".