21145531 has 8 divisors (see below), whose sum is σ = 23153328. Its totient is φ = 19152000.

The previous prime is 21145519. The next prime is 21145543. The reversal of 21145531 is 13554112.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21145519) and next prime (21145543).

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

It is a cyclic number.

It is not a de Polignac number, because 21145531 - 2⁷ = 21145403 is a prime.

It is a super-2 number, since 2×21145531² = 894266962543922, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21145511) 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, 330 + ... + 6511.

It is an arithmetic number, because the mean of its divisors is an integer number (2894166).

Almost surely, 2^21145531 is an apocalyptic number.

21145531 is a deficient number, since it is larger than the sum of its proper divisors (2007797).

21145531 is a wasteful number, since it uses less digits than its factorization.

21145531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7133.

The product of its digits is 600, while the sum is 22.

The square root of 21145531 is about 4598.4270136646. The cubic root of 21145531 is about 276.5282669343.

Adding to 21145531 its reverse (13554112), we get a palindrome (34699643).

The spelling of 21145531 in words is "twenty-one million, one hundred forty-five thousand, five hundred thirty-one".