21698518051 has 6 divisors (see below), whose sum is σ = 25241133300. Its totient is φ = 18598729716.

The previous prime is 21698518043. The next prime is 21698518081. The reversal of 21698518051 is 15081589612.

It is a happy number.

It is not a de Polignac number, because 21698518051 - 2³ = 21698518043 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21698517992 and 21698518010.

It is not an unprimeable number, because it can be changed into a prime (21698518001) 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, 221413401 + ... + 221413498.

It is an arithmetic number, because the mean of its divisors is an integer number (4206855550).

Almost surely, 2^21698518051 is an apocalyptic number.

21698518051 is a deficient number, since it is larger than the sum of its proper divisors (3542615249).

21698518051 is an equidigital number, since it uses as much as digits as its factorization.

21698518051 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 442826913 (or 442826906 counting only the distinct ones).

The product of its (nonzero) digits is 172800, while the sum is 46.

The spelling of 21698518051 in words is "twenty-one billion, six hundred ninety-eight million, five hundred eighteen thousand, fifty-one".