21515445508751 has 2 divisors, whose sum is σ = 21515445508752. Its totient is φ = 21515445508750.

The previous prime is 21515445508741. The next prime is 21515445508763. The reversal of 21515445508751 is 15780554451512.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21515445508751 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21515445508693 and 21515445508702.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21515445508741) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10757722754375 + 10757722754376.

It is an arithmetic number, because the mean of its divisors is an integer number (10757722754376).

Almost surely, 2^{21515445508751} is an apocalyptic number.

21515445508751 is a deficient number, since it is larger than the sum of its proper divisors (1).

21515445508751 is an equidigital number, since it uses as much as digits as its factorization.

21515445508751 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5600000, while the sum is 53.

The spelling of 21515445508751 in words is "twenty-one trillion, five hundred fifteen billion, four hundred forty-five million, five hundred eight thousand, seven hundred fifty-one".