20845551 has 4 divisors (see below), whose sum is σ = 27794072. Its totient is φ = 13897032.

The previous prime is 20845543. The next prime is 20845579. The reversal of 20845551 is 15554802.

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

It is not a de Polignac number, because 20845551 - 2³ = 20845543 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 (20845501) 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, 3474256 + ... + 3474261.

It is an arithmetic number, because the mean of its divisors is an integer number (6948518).

Almost surely, 2^20845551 is an apocalyptic number.

20845551 is a deficient number, since it is larger than the sum of its proper divisors (6948521).

20845551 is an equidigital number, since it uses as much as digits as its factorization.

20845551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6948520.

The product of its (nonzero) digits is 8000, while the sum is 30.

The square root of 20845551 is about 4565.6928280383. The cubic root of 20845551 is about 275.2143826918.

The spelling of 20845551 in words is "twenty million, eight hundred forty-five thousand, five hundred fifty-one".