21535131 has 16 divisors (see below), whose sum is σ = 29617280. Its totient is φ = 13910400.

The previous prime is 21535123. The next prime is 21535169. The reversal of 21535131 is 13153512.

It is not a de Polignac number, because 21535131 - 2³ = 21535123 is a prime.

It is a super-2 number, since 2×21535131² = 927523734374322, which contains 22 as substring.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a junction number, because it is equal to n+sod(n) for n = 21535098 and 21535107.

It is not an unprimeable number, because it can be changed into a prime (21535121) 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, 17331 + ... + 18531.

It is an arithmetic number, because the mean of its divisors is an integer number (1851080).

Almost surely, 2^21535131 is an apocalyptic number.

21535131 is a deficient number, since it is larger than the sum of its proper divisors (8082149).

21535131 is a wasteful number, since it uses less digits than its factorization.

21535131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1386.

The product of its digits is 450, while the sum is 21.

The square root of 21535131 is about 4640.5959746567. The cubic root of 21535131 is about 278.2162585855.

Adding to 21535131 its reverse (13153512), we get a palindrome (34688643).

The spelling of 21535131 in words is "twenty-one million, five hundred thirty-five thousand, one hundred thirty-one".