21161345 has 16 divisors (see below), whose sum is σ = 28304640. Its totient is φ = 15093504.

The previous prime is 21161323. The next prime is 21161377. The reversal of 21161345 is 54316112.

It is a cyclic number.

It is not a de Polignac number, because 21161345 - 2⁶ = 21161281 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21161345.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4937 + ... + 8166.

It is an arithmetic number, because the mean of its divisors is an integer number (1769040).

Almost surely, 2^21161345 is an apocalyptic number.

It is an amenable number.

21161345 is a deficient number, since it is larger than the sum of its proper divisors (7143295).

21161345 is a wasteful number, since it uses less digits than its factorization.

21161345 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13144.

The product of its digits is 720, while the sum is 23.

The square root of 21161345 is about 4600.1461933291. The cubic root of 21161345 is about 276.5971850164.

Adding to 21161345 its reverse (54316112), we get a palindrome (75477457).

The spelling of 21161345 in words is "twenty-one million, one hundred sixty-one thousand, three hundred forty-five".