400421000123981 has 2 divisors, whose sum is σ = 400421000123982. Its totient is φ = 400421000123980.

The previous prime is 400421000123939. The next prime is 400421000124037. The reversal of 400421000123981 is 189321000124004.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 256654305548356 + 143766694575625 = 16020434^2 + 11990275^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-400421000123981 is a prime.

It is a super-2 number, since 2×400421000123981² (a number of 30 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (400421300123981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 200210500061990 + 200210500061991.

It is an arithmetic number, because the mean of its divisors is an integer number (200210500061991).

Almost surely, 2^{400421000123981} is an apocalyptic number.

It is an amenable number.

400421000123981 is a deficient number, since it is larger than the sum of its proper divisors (1).

400421000123981 is an equidigital number, since it uses as much as digits as its factorization.

400421000123981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 13824, while the sum is 35.

Adding to 400421000123981 its reverse (189321000124004), we get a palindrome (589742000247985).

The spelling of 400421000123981 in words is "four hundred trillion, four hundred twenty-one billion, one hundred twenty-three thousand, nine hundred eighty-one".