20775551 has 4 divisors (see below), whose sum is σ = 21217632. Its totient is φ = 20333472.

The previous prime is 20775541. The next prime is 20775577. The reversal of 20775551 is 15557702.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20775551 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 (20775511) 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, 220970 + ... + 221063.

It is an arithmetic number, because the mean of its divisors is an integer number (5304408).

Almost surely, 2^20775551 is an apocalyptic number.

20775551 is a deficient number, since it is larger than the sum of its proper divisors (442081).

20775551 is an equidigital number, since it uses as much as digits as its factorization.

20775551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 442080.

The product of its (nonzero) digits is 12250, while the sum is 32.

The square root of 20775551 is about 4558.0205133369. The cubic root of 20775551 is about 274.9059777749.

The spelling of 20775551 in words is "twenty million, seven hundred seventy-five thousand, five hundred fifty-one".