21003056506 has 16 divisors (see below), whose sum is σ = 31653276480. Its totient is φ = 10451993760.

The previous prime is 21003056489. The next prime is 21003056561. The reversal of 21003056506 is 60565030012.

It is a super-2 number, since 2×21003056506² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2155726 + ... + 2165446.

It is an arithmetic number, because the mean of its divisors is an integer number (1978329780).

Almost surely, 2^21003056506 is an apocalyptic number.

21003056506 is a deficient number, since it is larger than the sum of its proper divisors (10650219974).

21003056506 is a wasteful number, since it uses less digits than its factorization.

21003056506 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14709.

The product of its (nonzero) digits is 5400, while the sum is 28.

Adding to 21003056506 its reverse (60565030012), we get a palindrome (81568086518).

The spelling of 21003056506 in words is "twenty-one billion, three million, fifty-six thousand, five hundred six".