20551521 has 32 divisors (see below), whose sum is σ = 30965760. Its totient is φ = 12047616.

The previous prime is 20551511. The next prime is 20551523. The reversal of 20551521 is 12515502.

It is not a de Polignac number, because 20551521 - 2⁷ = 20551393 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20551523) 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 31 ways as a sum of consecutive naturals, for example, 122980 + ... + 123146.

It is an arithmetic number, because the mean of its divisors is an integer number (967680).

Almost surely, 2^20551521 is an apocalyptic number.

It is an amenable number.

20551521 is a deficient number, since it is larger than the sum of its proper divisors (10414239).

20551521 is a wasteful number, since it uses less digits than its factorization.

20551521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 333.

The product of its (nonzero) digits is 500, while the sum is 21.

The square root of 20551521 is about 4533.3785414413. The cubic root of 20551521 is about 273.9142689145.

The spelling of 20551521 in words is "twenty million, five hundred fifty-one thousand, five hundred twenty-one".