21515410554457 has 2 divisors, whose sum is σ = 21515410554458. Its totient is φ = 21515410554456.

The previous prime is 21515410554371. The next prime is 21515410554493. The reversal of 21515410554457 is 75445501451512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21515301894681 + 108659776 = 4638459^2 + 10424^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21515410554457 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21515410554457.

It is not a weakly prime, because it can be changed into another prime (21515410554497) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10757705277228 + 10757705277229.

It is an arithmetic number, because the mean of its divisors is an integer number (10757705277229).

Almost surely, 2^{21515410554457} is an apocalyptic number.

It is an amenable number.

21515410554457 is a deficient number, since it is larger than the sum of its proper divisors (1).

21515410554457 is an equidigital number, since it uses as much as digits as its factorization.

21515410554457 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2800000, while the sum is 49.

The spelling of 21515410554457 in words is "twenty-one trillion, five hundred fifteen billion, four hundred ten million, five hundred fifty-four thousand, four hundred fifty-seven".