1561606651 has 4 divisors (see below), whose sum is σ = 1703570904. Its totient is φ = 1419642400.

The previous prime is 1561606633. The next prime is 1561606699. The reversal of 1561606651 is 1566061651.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 1561606651 - 2⁹ = 1561606139 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1561606651.

It is not an unprimeable number, because it can be changed into a prime (1561606951) 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, 70982110 + ... + 70982131.

It is an arithmetic number, because the mean of its divisors is an integer number (425892726).

Almost surely, 2^1561606651 is an apocalyptic number.

1561606651 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1561606651 is a deficient number, since it is larger than the sum of its proper divisors (141964253).

1561606651 is a wasteful number, since it uses less digits than its factorization.

1561606651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 141964252.

The product of its (nonzero) digits is 32400, while the sum is 37.

The square root of 1561606651 is about 39517.1690661161. The cubic root of 1561606651 is about 1160.1760164432.

The spelling of 1561606651 in words is "one billion, five hundred sixty-one million, six hundred six thousand, six hundred fifty-one".