21904416087551 has 4 divisors (see below), whose sum is σ = 21925022312592. Its totient is φ = 21883809862512.

The previous prime is 21904416087539. The next prime is 21904416087559. The reversal of 21904416087551 is 15578061440912.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21904416087551 - 2³⁰ = 21903342345727 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21904416087493 and 21904416087502.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21904416087559) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10303110926 + ... + 10303113051.

It is an arithmetic number, because the mean of its divisors is an integer number (5481255578148).

Almost surely, 2^{21904416087551} is an apocalyptic number.

21904416087551 is a deficient number, since it is larger than the sum of its proper divisors (20606225041).

21904416087551 is a wasteful number, since it uses less digits than its factorization.

21904416087551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20606225040.

The product of its (nonzero) digits is 2419200, while the sum is 53.

The spelling of 21904416087551 in words is "twenty-one trillion, nine hundred four billion, four hundred sixteen million, eighty-seven thousand, five hundred fifty-one".