21056545155999 has 32 divisors (see below), whose sum is σ = 29792171407360. Its totient is φ = 13205342390400.

The previous prime is 21056545155973. The next prime is 21056545156021. The reversal of 21056545155999 is 99955154565012.

It is not a de Polignac number, because 21056545155999 - 2⁵ = 21056545155967 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21056545155929) 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, 816264 + ... + 6540594.

It is an arithmetic number, because the mean of its divisors is an integer number (931005356480).

Almost surely, 2^{21056545155999} is an apocalyptic number.

21056545155999 is a deficient number, since it is larger than the sum of its proper divisors (8735626251361).

21056545155999 is a wasteful number, since it uses less digits than its factorization.

21056545155999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5725471.

The product of its (nonzero) digits is 109350000, while the sum is 66.

The spelling of 21056545155999 in words is "twenty-one trillion, fifty-six billion, five hundred forty-five million, one hundred fifty-five thousand, nine hundred ninety-nine".