1561363651 has 4 divisors (see below), whose sum is σ = 1561608472. Its totient is φ = 1561118832.

The previous prime is 1561363607. The next prime is 1561363667. The reversal of 1561363651 is 1563631651.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1563631651 = 71 ⋅22022981.

It is a cyclic number.

It is not a de Polignac number, because 1561363651 - 2¹¹ = 1561361603 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 1561363651.

It is not an unprimeable number, because it can be changed into a prime (1261363651) 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, 112581 + ... + 125686.

It is an arithmetic number, because the mean of its divisors is an integer number (390402118).

Almost surely, 2^1561363651 is an apocalyptic number.

1561363651 is a deficient number, since it is larger than the sum of its proper divisors (244821).

1561363651 is an equidigital number, since it uses as much as digits as its factorization.

1561363651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 244820.

The product of its digits is 48600, while the sum is 37.

The square root of 1561363651 is about 39514.0943335413. The cubic root of 1561363651 is about 1160.1158353905.

The spelling of 1561363651 in words is "one billion, five hundred sixty-one million, three hundred sixty-three thousand, six hundred fifty-one".