21161031 has 8 divisors (see below), whose sum is σ = 28871040. Its totient is φ = 13779192.

The previous prime is 21161027. The next prime is 21161033. The reversal of 21161031 is 13016112.

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

It is not a de Polignac number, because 21161031 - 2² = 21161027 is a prime.

It is a super-2 number, since 2×21161031² = 895578465965922, 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 21161031.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21161033) 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 7 ways as a sum of consecutive naturals, for example, 81891 + ... + 82148.

It is an arithmetic number, because the mean of its divisors is an integer number (3608880).

Almost surely, 2^21161031 is an apocalyptic number.

21161031 is a deficient number, since it is larger than the sum of its proper divisors (7710009).

21161031 is a wasteful number, since it uses less digits than its factorization.

21161031 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 164085.

The product of its (nonzero) digits is 36, while the sum is 15.

The square root of 21161031 is about 4600.1120638524. The cubic root of 21161031 is about 276.5958169253.

Adding to 21161031 its reverse (13016112), we get a palindrome (34177143).

The spelling of 21161031 in words is "twenty-one million, one hundred sixty-one thousand, thirty-one".