20887945 has 16 divisors (see below), whose sum is σ = 27139392. Its totient is φ = 15341760.

The previous prime is 20887939. The next prime is 20887949. The reversal of 20887945 is 54978802.

It is not a de Polignac number, because 20887945 - 2⁵ = 20887913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20887949) 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, 12954 + ... + 14476.

It is an arithmetic number, because the mean of its divisors is an integer number (1696212).

Almost surely, 2^20887945 is an apocalyptic number.

It is an amenable number.

20887945 is a deficient number, since it is larger than the sum of its proper divisors (6251447).

20887945 is a wasteful number, since it uses less digits than its factorization.

20887945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1752.

The product of its (nonzero) digits is 161280, while the sum is 43.

The square root of 20887945 is about 4570.3331388423. Note that the first 3 decimals coincide. The cubic root of 20887945 is about 275.4008259610.

The spelling of 20887945 in words is "twenty million, eight hundred eighty-seven thousand, nine hundred forty-five".