15555320657 has 2 divisors, whose sum is σ = 15555320658. Its totient is φ = 15555320656.

The previous prime is 15555320629. The next prime is 15555320663. The reversal of 15555320657 is 75602355551.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8856880321 + 6698440336 = 94111^2 + 81844^2 .

It is a cyclic number.

It is not a de Polignac number, because 15555320657 - 2⁶ = 15555320593 is a prime.

It is not a weakly prime, because it can be changed into another prime (15555320687) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7777660328 + 7777660329.

It is an arithmetic number, because the mean of its divisors is an integer number (7777660329).

Almost surely, 2^15555320657 is an apocalyptic number.

It is an amenable number.

15555320657 is a deficient number, since it is larger than the sum of its proper divisors (1).

15555320657 is an equidigital number, since it uses as much as digits as its factorization.

15555320657 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 787500, while the sum is 44.

The spelling of 15555320657 in words is "fifteen billion, five hundred fifty-five million, three hundred twenty thousand, six hundred fifty-seven".