21400394181 has 8 divisors (see below), whose sum is σ = 28566177120. Its totient is φ = 14250770352.

The previous prime is 21400394167. The next prime is 21400394201. The reversal of 21400394181 is 18149300412.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21400394181 - 2¹⁸ = 21400132037 is a prime.

It is a super-2 number, since 2×21400394181² (a number of 21 digits) contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21400394161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4036686 + ... + 4041983.

It is an arithmetic number, because the mean of its divisors is an integer number (3570772140).

Almost surely, 2^21400394181 is an apocalyptic number.

It is an amenable number.

21400394181 is a deficient number, since it is larger than the sum of its proper divisors (7165782939).

21400394181 is an equidigital number, since it uses as much as digits as its factorization.

21400394181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8079555.

The product of its (nonzero) digits is 6912, while the sum is 33.

Adding to 21400394181 its reverse (18149300412), we get a palindrome (39549694593).

The spelling of 21400394181 in words is "twenty-one billion, four hundred million, three hundred ninety-four thousand, one hundred eighty-one".