1561166651 has 4 divisors (see below), whose sum is σ = 1703090904. Its totient is φ = 1419242400.

The previous prime is 1561166549. The next prime is 1561166669. The reversal of 1561166651 is 1566611651.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1566611651 = 11 ⋅142419241.

It is a cyclic number.

It is not a de Polignac number, because 1561166651 - 2²⁶ = 1494057787 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1561166681) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 70962110 + ... + 70962131.

It is an arithmetic number, because the mean of its divisors is an integer number (425772726).

Almost surely, 2^1561166651 is an apocalyptic number.

1561166651 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1561166651 is a deficient number, since it is larger than the sum of its proper divisors (141924253).

1561166651 is a wasteful number, since it uses less digits than its factorization.

1561166651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 141924252.

The product of its digits is 32400, while the sum is 38.

The square root of 1561166651 is about 39511.6014734913. The cubic root of 1561166651 is about 1160.0670420527.

The spelling of 1561166651 in words is "one billion, five hundred sixty-one million, one hundred sixty-six thousand, six hundred fifty-one".