21318851077 has 4 divisors (see below), whose sum is σ = 21319145260. Its totient is φ = 21318556896.

The previous prime is 21318851053. The next prime is 21318851101. The reversal of 21318851077 is 77015881312.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is an interprime number because it is at equal distance from previous prime (21318851053) and next prime (21318851101).

It can be written as a sum of positive squares in 2 ways, for example, as 10429719876 + 10889131201 = 102126^2 + 104351^2 .

It is a cyclic number.

It is not a de Polignac number, because 21318851077 - 2²³ = 21310462469 is a prime.

It is a super-2 number, since 2×21318851077² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21318851027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 46843 + ... + 211735.

It is an arithmetic number, because the mean of its divisors is an integer number (5329786315).

Almost surely, 2^21318851077 is an apocalyptic number.

It is an amenable number.

21318851077 is a deficient number, since it is larger than the sum of its proper divisors (294183).

21318851077 is a wasteful number, since it uses less digits than its factorization.

21318851077 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 294182.

The product of its (nonzero) digits is 94080, while the sum is 43.

The spelling of 21318851077 in words is "twenty-one billion, three hundred eighteen million, eight hundred fifty-one thousand, seventy-seven".