21521383 has 16 divisors (see below), whose sum is σ = 24093216. Its totient is φ = 19094400.

The previous prime is 21521369. The next prime is 21521387. The reversal of 21521383 is 38312512.

It is a de Polignac number, because none of the positive numbers 2^k-21521383 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21521387) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 48360 + ... + 48802.

It is an arithmetic number, because the mean of its divisors is an integer number (1505826).

Almost surely, 2^21521383 is an apocalyptic number.

21521383 is a deficient number, since it is larger than the sum of its proper divisors (2571833).

21521383 is a wasteful number, since it uses less digits than its factorization.

21521383 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 594.

The product of its digits is 1440, while the sum is 25.

The square root of 21521383 is about 4639.1144629121. The cubic root of 21521383 is about 278.1570416815.

Adding to 21521383 its reverse (38312512), we get a palindrome (59833895).

It can be divided in two parts, 215213 and 83, that added together give a square (215296 = 464²).

The spelling of 21521383 in words is "twenty-one million, five hundred twenty-one thousand, three hundred eighty-three".