21106475551 has 6 divisors (see below), whose sum is σ = 24552430800. Its totient is φ = 18091264716.

The previous prime is 21106475501. The next prime is 21106475563. The reversal of 21106475551 is 15557460112.

It is not a de Polignac number, because 21106475551 - 2¹⁹ = 21105951263 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 21106475551.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21106475501) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 215372151 + ... + 215372248.

It is an arithmetic number, because the mean of its divisors is an integer number (4092071800).

Almost surely, 2^21106475551 is an apocalyptic number.

21106475551 is a deficient number, since it is larger than the sum of its proper divisors (3445955249).

21106475551 is an equidigital number, since it uses as much as digits as its factorization.

21106475551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 430744413 (or 430744406 counting only the distinct ones).

The product of its (nonzero) digits is 42000, while the sum is 37.

The spelling of 21106475551 in words is "twenty-one billion, one hundred six million, four hundred seventy-five thousand, five hundred fifty-one".