21516022177 has 4 divisors (see below), whose sum is σ = 23171100820. Its totient is φ = 19860943536.

The previous prime is 21516022141. The next prime is 21516022193. The reversal of 21516022177 is 77122061512.

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

It can be written as a sum of positive squares in 2 ways, for example, as 12596919696 + 8919102481 = 112236^2 + 94441^2 .

It is a cyclic number.

It is not a de Polignac number, because 21516022177 - 2⁷ = 21516022049 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21516022277) 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, 827539302 + ... + 827539327.

It is an arithmetic number, because the mean of its divisors is an integer number (5792775205).

Almost surely, 2^21516022177 is an apocalyptic number.

It is an amenable number.

21516022177 is a deficient number, since it is larger than the sum of its proper divisors (1655078643).

21516022177 is a wasteful number, since it uses less digits than its factorization.

21516022177 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1655078642.

The product of its (nonzero) digits is 11760, while the sum is 34.

Adding to 21516022177 its reverse (77122061512), we get a palindrome (98638083689).

The spelling of 21516022177 in words is "twenty-one billion, five hundred sixteen million, twenty-two thousand, one hundred seventy-seven".