21378181009 has 32 divisors (see below), whose sum is σ = 22752576000. Its totient is φ = 20064844800.

The previous prime is 21378180979. The next prime is 21378181039. The reversal of 21378181009 is 90018187312.

It is an interprime number because it is at equal distance from previous prime (21378180979) and next prime (21378181039).

It is a cyclic number.

It is not a de Polignac number, because 21378181009 - 2⁵ = 21378180977 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21378181039) 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 31 ways as a sum of consecutive naturals, for example, 23466264 + ... + 23467174.

It is an arithmetic number, because the mean of its divisors is an integer number (711018000).

Almost surely, 2^21378181009 is an apocalyptic number.

It is an amenable number.

21378181009 is a deficient number, since it is larger than the sum of its proper divisors (1374394991).

21378181009 is a wasteful number, since it uses less digits than its factorization.

21378181009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1209.

The product of its (nonzero) digits is 24192, while the sum is 40.

The spelling of 21378181009 in words is "twenty-one billion, three hundred seventy-eight million, one hundred eighty-one thousand, nine".