20947284 has 18 divisors (see below), whose sum is σ = 52950170. Its totient is φ = 6982416.

The previous prime is 20947271. The next prime is 20947327. The reversal of 20947284 is 48274902.

It can be written as a sum of positive squares in only one way, i.e., 20903184 + 44100 = 4572^2 + 210^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 581869 = 20947284 / (2 + 0 + 9 + 4 + 7 + 2 + 8 + 4).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 290899 + ... + 290970.

Almost surely, 2^20947284 is an apocalyptic number.

It is an amenable number.

20947284 is an abundant number, since it is smaller than the sum of its proper divisors (32002886).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20947284 is a wasteful number, since it uses less digits than its factorization.

20947284 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 581879 (or 581874 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 36.

The square root of 20947284 is about 4576.8202936100. The cubic root of 20947284 is about 275.6613679316.

The spelling of 20947284 in words is "twenty million, nine hundred forty-seven thousand, two hundred eighty-four".