20556501 has 16 divisors (see below), whose sum is σ = 31488000. Its totient is φ = 11685168.

The previous prime is 20556493. The next prime is 20556517. The reversal of 20556501 is 10565502.

It is not a de Polignac number, because 20556501 - 2³ = 20556493 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20556521) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1720 + ... + 6638.

It is an arithmetic number, because the mean of its divisors is an integer number (1968000).

Almost surely, 2^20556501 is an apocalyptic number.

20556501 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20556501 is a deficient number, since it is larger than the sum of its proper divisors (10931499).

20556501 is a wasteful number, since it uses less digits than its factorization.

20556501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5128.

The product of its (nonzero) digits is 1500, while the sum is 24.

The square root of 20556501 is about 4533.9277673999. The cubic root of 20556501 is about 273.9363918982.

Subtracting from 20556501 its reverse (10565502), we obtain a palindrome (9990999).

The spelling of 20556501 in words is "twenty million, five hundred fifty-six thousand, five hundred one".