20931945 has 8 divisors (see below), whose sum is σ = 33491136. Its totient is φ = 11163696.

The previous prime is 20931943. The next prime is 20931949. The reversal of 20931945 is 54913902.

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

It is not a de Polignac number, because 20931945 - 2¹ = 20931943 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20931941) 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, 697717 + ... + 697746.

It is an arithmetic number, because the mean of its divisors is an integer number (4186392).

Almost surely, 2^20931945 is an apocalyptic number.

It is an amenable number.

20931945 is a deficient number, since it is larger than the sum of its proper divisors (12559191).

20931945 is a wasteful number, since it uses less digits than its factorization.

20931945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1395471.

The product of its (nonzero) digits is 9720, while the sum is 33.

The square root of 20931945 is about 4575.1442600207. The cubic root of 20931945 is about 275.5940656147.

The spelling of 20931945 in words is "twenty million, nine hundred thirty-one thousand, nine hundred forty-five".