20556001 has 4 divisors (see below), whose sum is σ = 20626452. Its totient is φ = 20485552.

The previous prime is 20555999. The next prime is 20556017. The reversal of 20556001 is 10065502.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 12006225 + 8549776 = 3465^2 + 2924^2 .

It is a cyclic number.

It is not a de Polignac number, because 20556001 - 2¹ = 20555999 is a prime.

It is a super-2 number, since 2×20556001² = 845098354224002, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20556001.

It is not an unprimeable number, because it can be changed into a prime (20556031) 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, 34786 + ... + 35371.

It is an arithmetic number, because the mean of its divisors is an integer number (5156613).

Almost surely, 2^20556001 is an apocalyptic number.

It is an amenable number.

20556001 is a deficient number, since it is larger than the sum of its proper divisors (70451).

20556001 is an equidigital number, since it uses as much as digits as its factorization.

20556001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70450.

The product of its (nonzero) digits is 300, while the sum is 19.

The square root of 20556001 is about 4533.8726272360. The cubic root of 20556001 is about 273.9341708765.

The spelling of 20556001 in words is "twenty million, five hundred fifty-six thousand, one".