20949847 has 4 divisors (see below), whose sum is σ = 21090600. Its totient is φ = 20809096.

The previous prime is 20949833. The next prime is 20949857. The reversal of 20949847 is 74894902.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20949847 - 2¹¹ = 20947799 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20949857) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 70153 + ... + 70450.

It is an arithmetic number, because the mean of its divisors is an integer number (5272650).

Almost surely, 2^20949847 is an apocalyptic number.

20949847 is a deficient number, since it is larger than the sum of its proper divisors (140753).

20949847 is a wasteful number, since it uses less digits than its factorization.

20949847 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 140752.

The product of its (nonzero) digits is 145152, while the sum is 43.

The square root of 20949847 is about 4577.1002829302. The cubic root of 20949847 is about 275.6726103004.

The spelling of 20949847 in words is "twenty million, nine hundred forty-nine thousand, eight hundred forty-seven".