21150531 has 16 divisors (see below), whose sum is σ = 31410720. Its totient is φ = 14065920.

The previous prime is 21150523. The next prime is 21150607. The reversal of 21150531 is 13505112.

It is not a de Polignac number, because 21150531 - 2³ = 21150523 is a prime.

It is a super-2 number, since 2×21150531² = 894689923163922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21150331) 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, 15351 + ... + 16671.

It is an arithmetic number, because the mean of its divisors is an integer number (1963170).

Almost surely, 2^21150531 is an apocalyptic number.

21150531 is a deficient number, since it is larger than the sum of its proper divisors (10260189).

21150531 is a wasteful number, since it uses less digits than its factorization.

21150531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1923 (or 1917 counting only the distinct ones).

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

The square root of 21150531 is about 4598.9706456989. The cubic root of 21150531 is about 276.5500608597.

Adding to 21150531 its reverse (13505112), we get a palindrome (34655643).

The spelling of 21150531 in words is "twenty-one million, one hundred fifty thousand, five hundred thirty-one".