21544403353987 has 2 divisors, whose sum is σ = 21544403353988. Its totient is φ = 21544403353986.

The previous prime is 21544403353901. The next prime is 21544403354021. The reversal of 21544403353987 is 78935330444512.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21544403353987 is a prime.

It is a super-2 number, since 2×21544403353987² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21544403353087) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10772201676993 + 10772201676994.

It is an arithmetic number, because the mean of its divisors is an integer number (10772201676994).

Almost surely, 2^{21544403353987} is an apocalyptic number.

21544403353987 is a deficient number, since it is larger than the sum of its proper divisors (1).

21544403353987 is an equidigital number, since it uses as much as digits as its factorization.

21544403353987 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 43545600, while the sum is 58.

The spelling of 21544403353987 in words is "twenty-one trillion, five hundred forty-four billion, four hundred three million, three hundred fifty-three thousand, nine hundred eighty-seven".