21531123020505 has 32 divisors (see below), whose sum is σ = 41687149112064. Its totient is φ = 9263810912256.

The previous prime is 21531123020503. The next prime is 21531123020513. The reversal of 21531123020505 is 50502032113512.

It is not a de Polignac number, because 21531123020505 - 2¹ = 21531123020503 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21531123020503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 6031125112 + ... + 6031128681.

It is an arithmetic number, because the mean of its divisors is an integer number (1302723409752).

Almost surely, 2^{21531123020505} is an apocalyptic number.

It is an amenable number.

21531123020505 is a deficient number, since it is larger than the sum of its proper divisors (20156026091559).

21531123020505 is a wasteful number, since it uses less digits than its factorization.

21531123020505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12062253825.

The product of its (nonzero) digits is 9000, while the sum is 30.

The spelling of 21531123020505 in words is "twenty-one trillion, five hundred thirty-one billion, one hundred twenty-three million, twenty thousand, five hundred five".