21531051 has 12 divisors (see below), whose sum is σ = 31144360. Its totient is φ = 14333760.

The previous prime is 21531049. The next prime is 21531071. The reversal of 21531051 is 15013512.

It is not a de Polignac number, because 21531051 - 2¹ = 21531049 is a prime.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a zygodrome in base 3.

It is not an unprimeable number, because it can be changed into a prime (21531001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7896 + ... + 10266.

Almost surely, 2^21531051 is an apocalyptic number.

21531051 is a deficient number, since it is larger than the sum of its proper divisors (9613309).

21531051 is a wasteful number, since it uses less digits than its factorization.

21531051 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3386 (or 3383 counting only the distinct ones).

The product of its (nonzero) digits is 150, while the sum is 18.

The square root of 21531051 is about 4640.1563551243. The cubic root of 21531051 is about 278.1986873894.

Adding to 21531051 its reverse (15013512), we get a palindrome (36544563).

The spelling of 21531051 in words is "twenty-one million, five hundred thirty-one thousand, fifty-one".