21015556405043 has 2 divisors, whose sum is σ = 21015556405044. Its totient is φ = 21015556405042.

The previous prime is 21015556405001. The next prime is 21015556405133. The reversal of 21015556405043 is 34050465551012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21015556405043 - 2¹² = 21015556400947 is a prime.

It is a super-2 number, since 2×21015556405043² (a number of 27 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (21015556405243) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10507778202521 + 10507778202522.

It is an arithmetic number, because the mean of its divisors is an integer number (10507778202522).

Almost surely, 2^{21015556405043} is an apocalyptic number.

21015556405043 is a deficient number, since it is larger than the sum of its proper divisors (1).

21015556405043 is an equidigital number, since it uses as much as digits as its factorization.

21015556405043 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 360000, while the sum is 41.

The spelling of 21015556405043 in words is "twenty-one trillion, fifteen billion, five hundred fifty-six million, four hundred five thousand, forty-three".