1551561197 has 2 divisors, whose sum is σ = 1551561198. Its totient is φ = 1551561196.

The previous prime is 1551561113. The next prime is 1551561241. The reversal of 1551561197 is 7911651551.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1390245796 + 161315401 = 37286^2 + 12701^2 .

It is a cyclic number.

It is not a de Polignac number, because 1551561197 - 2²² = 1547366893 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1551561107) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 775780598 + 775780599.

It is an arithmetic number, because the mean of its divisors is an integer number (775780599).

Almost surely, 2^1551561197 is an apocalyptic number.

It is an amenable number.

1551561197 is a deficient number, since it is larger than the sum of its proper divisors (1).

1551561197 is an equidigital number, since it uses as much as digits as its factorization.

1551561197 is an evil number, because the sum of its binary digits is even.

The product of its digits is 47250, while the sum is 41.

The square root of 1551561197 is about 39389.8616016863. The cubic root of 1551561197 is about 1157.6829484410.

The spelling of 1551561197 in words is "one billion, five hundred fifty-one million, five hundred sixty-one thousand, one hundred ninety-seven".