21615115391999 has 2 divisors, whose sum is σ = 21615115392000. Its totient is φ = 21615115391998.

The previous prime is 21615115391981. The next prime is 21615115392019. The reversal of 21615115391999 is 99919351151612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21615115391999 - 2³² = 21610820424703 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21615115291999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10807557695999 + 10807557696000.

It is an arithmetic number, because the mean of its divisors is an integer number (10807557696000).

Almost surely, 2^{21615115391999} is an apocalyptic number.

21615115391999 is a deficient number, since it is larger than the sum of its proper divisors (1).

21615115391999 is an equidigital number, since it uses as much as digits as its factorization.

21615115391999 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5904900, while the sum is 62.

The spelling of 21615115391999 in words is "twenty-one trillion, six hundred fifteen billion, one hundred fifteen million, three hundred ninety-one thousand, nine hundred ninety-nine".