2556620021 has 8 divisors (see below), whose sum is σ = 2708100864. Its totient is φ = 2405260480.

The previous prime is 2556620009. The next prime is 2556620029. The reversal of 2556620021 is 1200266552.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2556620021 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 (2556620029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15026 + ... + 73068.

It is an arithmetic number, because the mean of its divisors is an integer number (338512608).

Almost surely, 2^2556620021 is an apocalyptic number.

It is an amenable number.

2556620021 is a deficient number, since it is larger than the sum of its proper divisors (151480843).

2556620021 is a wasteful number, since it uses less digits than its factorization.

2556620021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60651.

The product of its (nonzero) digits is 7200, while the sum is 29.

The square root of 2556620021 is about 50563.0301801623. The cubic root of 2556620021 is about 1367.3784418930.

Adding to 2556620021 its reverse (1200266552), we get a palindrome (3756886573).

The spelling of 2556620021 in words is "two billion, five hundred fifty-six million, six hundred twenty thousand, twenty-one".