21120531 has 8 divisors (see below), whose sum is σ = 28760064. Its totient is φ = 13780680.

The previous prime is 21120523. The next prime is 21120551. The reversal of 21120531 is 13502112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21120531 - 2³ = 21120523 is a prime.

It is a super-2 number, since 2×21120531² = 892153659443922, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21120531.

It is not an unprimeable number, because it can be changed into a prime (21120551) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 74755 + ... + 75036.

It is an arithmetic number, because the mean of its divisors is an integer number (3595008).

Almost surely, 2^21120531 is an apocalyptic number.

21120531 is a deficient number, since it is larger than the sum of its proper divisors (7639533).

21120531 is a wasteful number, since it uses less digits than its factorization.

21120531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 149841.

The product of its (nonzero) digits is 60, while the sum is 15.

The square root of 21120531 is about 4595.7078888894. The cubic root of 21120531 is about 276.4192457434.

Adding to 21120531 its reverse (13502112), we get a palindrome (34622643).

The spelling of 21120531 in words is "twenty-one million, one hundred twenty thousand, five hundred thirty-one".