21161518 has 16 divisors (see below), whose sum is σ = 37854720. Its totient is φ = 8674776.

The previous prime is 21161509. The next prime is 21161519. The reversal of 21161518 is 81516112.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 21161492 and 21161501.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21161519) 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, 32538 + ... + 33181.

It is an arithmetic number, because the mean of its divisors is an integer number (2365920).

Almost surely, 2^21161518 is an apocalyptic number.

21161518 is a deficient number, since it is larger than the sum of its proper divisors (16693202).

21161518 is a wasteful number, since it uses less digits than its factorization.

21161518 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65751.

The product of its digits is 480, while the sum is 25.

The square root of 21161518 is about 4600.1649970409. The cubic root of 21161518 is about 276.5979387679.

The spelling of 21161518 in words is "twenty-one million, one hundred sixty-one thousand, five hundred eighteen".