21306505742121 has 16 divisors (see below), whose sum is σ = 29911406182400. Its totient is φ = 13453348155408.

The previous prime is 21306505742113. The next prime is 21306505742173. The reversal of 21306505742121 is 12124750560312.

It is not a de Polignac number, because 21306505742121 - 2³ = 21306505742113 is a prime.

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 21306505742121.

It is not an unprimeable number, because it can be changed into a prime (21306505742101) 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, 46887361 + ... + 47339598.

It is an arithmetic number, because the mean of its divisors is an integer number (1869462886400).

Almost surely, 2^{21306505742121} is an apocalyptic number.

It is an amenable number.

21306505742121 is a deficient number, since it is larger than the sum of its proper divisors (8604900440279).

21306505742121 is a wasteful number, since it uses less digits than its factorization.

21306505742121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94230948.

The product of its (nonzero) digits is 100800, while the sum is 39.

The spelling of 21306505742121 in words is "twenty-one trillion, three hundred six billion, five hundred five million, seven hundred forty-two thousand, one hundred twenty-one".