21207775521345 has 32 divisors (see below), whose sum is σ = 38783123069952. Its totient is φ = 9694185423552.

The previous prime is 21207775521343. The next prime is 21207775521349. The reversal of 21207775521345 is 54312557770212.

It is not a de Polignac number, because 21207775521345 - 2¹ = 21207775521343 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21207775521343) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 7025887 + ... + 9580116.

It is an arithmetic number, because the mean of its divisors is an integer number (1211972595936).

Almost surely, 2^{21207775521345} is an apocalyptic number.

It is an amenable number.

21207775521345 is a deficient number, since it is larger than the sum of its proper divisors (17575347548607).

21207775521345 is a wasteful number, since it uses less digits than its factorization.

21207775521345 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16618181.

The product of its (nonzero) digits is 4116000, while the sum is 51.

The spelling of 21207775521345 in words is "twenty-one trillion, two hundred seven billion, seven hundred seventy-five million, five hundred twenty-one thousand, three hundred forty-five".