21100347878665 has 32 divisors (see below), whose sum is σ = 27838483190784. Its totient is φ = 15225927138240.

The previous prime is 21100347878647. The next prime is 21100347878681. The reversal of 21100347878665 is 56687874300112.

It is not a de Polignac number, because 21100347878665 - 2⁴³ = 12304254856457 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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, 2924322 + ... + 7124068.

It is an arithmetic number, because the mean of its divisors is an integer number (869952599712).

Almost surely, 2^{21100347878665} is an apocalyptic number.

It is an amenable number.

21100347878665 is a deficient number, since it is larger than the sum of its proper divisors (6738135312119).

21100347878665 is a wasteful number, since it uses less digits than its factorization.

21100347878665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4200477.

The product of its (nonzero) digits is 13547520, while the sum is 58.

The spelling of 21100347878665 in words is "twenty-one trillion, one hundred billion, three hundred forty-seven million, eight hundred seventy-eight thousand, six hundred sixty-five".