1561244251 has 8 divisors (see below), whose sum is σ = 1810910720. Its totient is φ = 1318235688.

The previous prime is 1561244221. The next prime is 1561244257. The reversal of 1561244251 is 1524421651.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1561244251 - 2⁵ = 1561244219 is a prime.

It is a super-2 number, since 2×1561244251² = 4874967222561102002, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1561244257) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1663971 + ... + 1664908.

It is an arithmetic number, because the mean of its divisors is an integer number (226363840).

Almost surely, 2^1561244251 is an apocalyptic number.

1561244251 is a deficient number, since it is larger than the sum of its proper divisors (249666469).

1561244251 is an equidigital number, since it uses as much as digits as its factorization.

1561244251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3328953.

The product of its digits is 9600, while the sum is 31.

The square root of 1561244251 is about 39512.5834513513. The cubic root of 1561244251 is about 1160.0862626595.

The spelling of 1561244251 in words is "one billion, five hundred sixty-one million, two hundred forty-four thousand, two hundred fifty-one".