20949947 has 4 divisors (see below), whose sum is σ = 21202440. Its totient is φ = 20697456.

The previous prime is 20949937. The next prime is 20949949. The reversal of 20949947 is 74994902.

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 20949947 - 2⁶ = 20949883 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20949898 and 20949907.

It is not an unprimeable number, because it can be changed into a prime (20949949) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 126122 + ... + 126287.

It is an arithmetic number, because the mean of its divisors is an integer number (5300610).

Almost surely, 2^20949947 is an apocalyptic number.

20949947 is a deficient number, since it is larger than the sum of its proper divisors (252493).

20949947 is an equidigital number, since it uses as much as digits as its factorization.

20949947 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 252492.

The product of its (nonzero) digits is 163296, while the sum is 44.

The square root of 20949947 is about 4577.1112068640. Note that the first 3 decimals coincide. The cubic root of 20949947 is about 275.6730489228.

The spelling of 20949947 in words is "twenty million, nine hundred forty-nine thousand, nine hundred forty-seven".