21506731405699 has 2 divisors, whose sum is σ = 21506731405700. Its totient is φ = 21506731405698.

The previous prime is 21506731405651. The next prime is 21506731405729. The reversal of 21506731405699 is 99650413760512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21506731405699 - 2²⁹ = 21506194534787 is a prime.

It is not a weakly prime, because it can be changed into another prime (21506731415699) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10753365702849 + 10753365702850.

It is an arithmetic number, because the mean of its divisors is an integer number (10753365702850).

Almost surely, 2^{21506731405699} is an apocalyptic number.

21506731405699 is a deficient number, since it is larger than the sum of its proper divisors (1).

21506731405699 is an equidigital number, since it uses as much as digits as its factorization.

21506731405699 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12247200, while the sum is 58.

The spelling of 21506731405699 in words is "twenty-one trillion, five hundred six billion, seven hundred thirty-one million, four hundred five thousand, six hundred ninety-nine".