16551621257 has 2 divisors, whose sum is σ = 16551621258. Its totient is φ = 16551621256.

The previous prime is 16551621253. The next prime is 16551621263. The reversal of 16551621257 is 75212615561.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8845590601 + 7706030656 = 94051^2 + 87784^2 .

It is a cyclic number.

It is not a de Polignac number, because 16551621257 - 2² = 16551621253 is a prime.

It is not a weakly prime, because it can be changed into another prime (16551621253) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8275810628 + 8275810629.

It is an arithmetic number, because the mean of its divisors is an integer number (8275810629).

Almost surely, 2^16551621257 is an apocalyptic number.

It is an amenable number.

16551621257 is a deficient number, since it is larger than the sum of its proper divisors (1).

16551621257 is an equidigital number, since it uses as much as digits as its factorization.

16551621257 is an evil number, because the sum of its binary digits is even.

The product of its digits is 126000, while the sum is 41.

The spelling of 16551621257 in words is "sixteen billion, five hundred fifty-one million, six hundred twenty-one thousand, two hundred fifty-seven".