400436081621 has 2 divisors, whose sum is σ = 400436081622. Its totient is φ = 400436081620.

The previous prime is 400436081609. The next prime is 400436081627. The reversal of 400436081621 is 126180634004.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 276795940996 + 123640140625 = 526114^2 + 351625^2 .

It is a cyclic number.

It is not a de Polignac number, because 400436081621 - 2¹⁸ = 400435819477 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (400436081627) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 200218040810 + 200218040811.

It is an arithmetic number, because the mean of its divisors is an integer number (200218040811).

Almost surely, 2^400436081621 is an apocalyptic number.

It is an amenable number.

400436081621 is a deficient number, since it is larger than the sum of its proper divisors (1).

400436081621 is an equidigital number, since it uses as much as digits as its factorization.

400436081621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 27648, while the sum is 35.

The spelling of 400436081621 in words is "four hundred billion, four hundred thirty-six million, eighty-one thousand, six hundred twenty-one".