21615544045547 has 2 divisors, whose sum is σ = 21615544045548. Its totient is φ = 21615544045546.

The previous prime is 21615544045523. The next prime is 21615544045567. The reversal of 21615544045547 is 74554044551612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21615544045547 - 2¹⁶ = 21615543980011 is a prime.

It is not a weakly prime, because it can be changed into another prime (21615544045567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10807772022773 + 10807772022774.

It is an arithmetic number, because the mean of its divisors is an integer number (10807772022774).

Almost surely, 2^{21615544045547} is an apocalyptic number.

21615544045547 is a deficient number, since it is larger than the sum of its proper divisors (1).

21615544045547 is an equidigital number, since it uses as much as digits as its factorization.

21615544045547 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 13440000, while the sum is 53.

The spelling of 21615544045547 in words is "twenty-one trillion, six hundred fifteen billion, five hundred forty-four million, forty-five thousand, five hundred forty-seven".