21646345 has 16 divisors (see below), whose sum is σ = 29795328. Its totient is φ = 14788800.

The previous prime is 21646337. The next prime is 21646349. The reversal of 21646345 is 54364612.

It is not a de Polignac number, because 21646345 - 2³ = 21646337 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21646349) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10120 + ... + 12070.

It is an arithmetic number, because the mean of its divisors is an integer number (1862208).

Almost surely, 2^21646345 is an apocalyptic number.

It is an amenable number.

21646345 is a deficient number, since it is larger than the sum of its proper divisors (8148983).

21646345 is a wasteful number, since it uses less digits than its factorization.

21646345 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2280.

The product of its digits is 17280, while the sum is 31.

The square root of 21646345 is about 4652.5632720039. The cubic root of 21646345 is about 278.6943677646.

The spelling of 21646345 in words is "twenty-one million, six hundred forty-six thousand, three hundred forty-five".