21051131 has 4 divisors (see below), whose sum is σ = 21067200. Its totient is φ = 21035064.

The previous prime is 21051103. The next prime is 21051137. The reversal of 21051131 is 13115012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21051131 - 2¹⁴ = 21034747 is a prime.

It is a super-2 number, since 2×21051131² = 886300232758322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21051137) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5876 + ... + 8753.

It is an arithmetic number, because the mean of its divisors is an integer number (5266800).

Almost surely, 2^21051131 is an apocalyptic number.

21051131 is a deficient number, since it is larger than the sum of its proper divisors (16069).

21051131 is a wasteful number, since it uses less digits than its factorization.

21051131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16068.

The product of its (nonzero) digits is 30, while the sum is 14.

The square root of 21051131 is about 4588.1511526976. The cubic root of 21051131 is about 276.1161513153.

Adding to 21051131 its reverse (13115012), we get a palindrome (34166143).

The spelling of 21051131 in words is "twenty-one million, fifty-one thousand, one hundred thirty-one".