20523551 has 4 divisors (see below), whose sum is σ = 20735232. Its totient is φ = 20311872.

The previous prime is 20523541. The next prime is 20523557. The reversal of 20523551 is 15532502.

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 20523551 - 2¹⁸ = 20261407 is a prime.

It is a super-2 number, since 2×20523551² = 842432291299202, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20523557) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 105695 + ... + 105888.

It is an arithmetic number, because the mean of its divisors is an integer number (5183808).

Almost surely, 2^20523551 is an apocalyptic number.

20523551 is a deficient number, since it is larger than the sum of its proper divisors (211681).

20523551 is an equidigital number, since it uses as much as digits as its factorization.

20523551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 211680.

The product of its (nonzero) digits is 1500, while the sum is 23.

The square root of 20523551 is about 4530.2925954071. The cubic root of 20523551 is about 273.7899494806.

The spelling of 20523551 in words is "twenty million, five hundred twenty-three thousand, five hundred fifty-one".