21506205516146 has 32 divisors (see below), whose sum is σ = 34956515415360. Its totient is φ = 9864315203904.

The previous prime is 21506205516079. The next prime is 21506205516149. The reversal of 21506205516146 is 64161550260512.

It is a junction number, because it is equal to n+sod(n) for n = 21506205516097 and 21506205516106.

It is not an unprimeable number, because it can be changed into a prime (21506205516149) 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, 59274041 + ... + 59635763.

It is an arithmetic number, because the mean of its divisors is an integer number (1092391106730).

Almost surely, 2^{21506205516146} is an apocalyptic number.

21506205516146 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21506205516146 is a deficient number, since it is larger than the sum of its proper divisors (13450309899214).

21506205516146 is a wasteful number, since it uses less digits than its factorization.

21506205516146 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 375930.

The product of its (nonzero) digits is 432000, while the sum is 44.

Adding to 21506205516146 its reverse (64161550260512), we get a palindrome (85667755776658).

The spelling of 21506205516146 in words is "twenty-one trillion, five hundred six billion, two hundred five million, five hundred sixteen thousand, one hundred forty-six".