21140831 has 8 divisors (see below), whose sum is σ = 21684624. Its totient is φ = 20603520.

The previous prime is 21140827. The next prime is 21140837. The reversal of 21140831 is 13804112.

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 21140831 - 2² = 21140827 is a prime.

It is a super-2 number, since 2×21140831² = 893869470741122, which contains 22 as substring.

It is a Duffinian number.

It is a zygodrome in base 4.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21140837) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5360 + ... + 8426.

It is an arithmetic number, because the mean of its divisors is an integer number (2710578).

Almost surely, 2^21140831 is an apocalyptic number.

21140831 is a deficient number, since it is larger than the sum of its proper divisors (543793).

21140831 is a wasteful number, since it uses less digits than its factorization.

21140831 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3241.

The product of its (nonzero) digits is 192, while the sum is 20.

The square root of 21140831 is about 4597.9159409454. The cubic root of 21140831 is about 276.5077775118.

Adding to 21140831 its reverse (13804112), we get a palindrome (34944943).

The spelling of 21140831 in words is "twenty-one million, one hundred forty thousand, eight hundred thirty-one".