1551565261 has 2 divisors, whose sum is σ = 1551565262. Its totient is φ = 1551565260.

The previous prime is 1551565241. The next prime is 1551565271. The reversal of 1551565261 is 1625651551.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1464516361 + 87048900 = 38269^2 + 9330^2 .

It is an emirp because it is prime and its reverse (1625651551) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1551565261 - 2⁵ = 1551565229 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1551565261.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1551565241) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 775782630 + 775782631.

It is an arithmetic number, because the mean of its divisors is an integer number (775782631).

Almost surely, 2^1551565261 is an apocalyptic number.

It is an amenable number.

1551565261 is a deficient number, since it is larger than the sum of its proper divisors (1).

1551565261 is an equidigital number, since it uses as much as digits as its factorization.

1551565261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 45000, while the sum is 37.

The square root of 1551565261 is about 39389.9131885309. The cubic root of 1551565261 is about 1157.6839592120.

The spelling of 1551565261 in words is "one billion, five hundred fifty-one million, five hundred sixty-five thousand, two hundred sixty-one".