21378031181 has 16 divisors (see below), whose sum is σ = 23830920960. Its totient is φ = 19041462720.

The previous prime is 21378031159. The next prime is 21378031183. The reversal of 21378031181 is 18113087312.

It is a happy number.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21378031181 is a prime.

It is a super-2 number, since 2×21378031181² (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 (21378031183) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 633116 + ... + 666026.

It is an arithmetic number, because the mean of its divisors is an integer number (1489432560).

Almost surely, 2^21378031181 is an apocalyptic number.

It is an amenable number.

21378031181 is a deficient number, since it is larger than the sum of its proper divisors (2452889779).

21378031181 is a wasteful number, since it uses less digits than its factorization.

21378031181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34676.

The product of its (nonzero) digits is 8064, while the sum is 35.

The spelling of 21378031181 in words is "twenty-one billion, three hundred seventy-eight million, thirty-one thousand, one hundred eighty-one".