21615498993577 has 2 divisors, whose sum is σ = 21615498993578. Its totient is φ = 21615498993576.

The previous prime is 21615498993409. The next prime is 21615498993643. The reversal of 21615498993577 is 77539989451612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16596693801216 + 5018805192361 = 4073904^2 + 2240269^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21615498993577 is a prime.

It is not a weakly prime, because it can be changed into another prime (21615498993377) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10807749496788 + 10807749496789.

It is an arithmetic number, because the mean of its divisors is an integer number (10807749496789).

Almost surely, 2^{21615498993577} is an apocalyptic number.

It is an amenable number.

21615498993577 is a deficient number, since it is larger than the sum of its proper divisors (1).

21615498993577 is an equidigital number, since it uses as much as digits as its factorization.

21615498993577 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1028764800, while the sum is 76.

The spelling of 21615498993577 in words is "twenty-one trillion, six hundred fifteen billion, four hundred ninety-eight million, nine hundred ninety-three thousand, five hundred seventy-seven".