1561251537 has 8 divisors (see below), whose sum is σ = 2312965280. Its totient is φ = 1040834340.

The previous prime is 1561251533. The next prime is 1561251541. The reversal of 1561251537 is 7351521651.

It is a happy number.

1561251537 is a `hidden beast` number, since 1 + 5 + 612 + 5 + 1 + 5 + 37 = 666.

It is an interprime number because it is at equal distance from previous prime (1561251533) and next prime (1561251541).

It is not a de Polignac number, because 1561251537 - 2² = 1561251533 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1561251533) 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, 28912039 + ... + 28912092.

It is an arithmetic number, because the mean of its divisors is an integer number (289120660).

Almost surely, 2^1561251537 is an apocalyptic number.

It is an amenable number.

1561251537 is a deficient number, since it is larger than the sum of its proper divisors (751713743).

1561251537 is an equidigital number, since it uses as much as digits as its factorization.

1561251537 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57824140 (or 57824134 counting only the distinct ones).

The product of its digits is 31500, while the sum is 36.

The square root of 1561251537 is about 39512.6756497203. The cubic root of 1561251537 is about 1160.0880672832.

The spelling of 1561251537 in words is "one billion, five hundred sixty-one million, two hundred fifty-one thousand, five hundred thirty-seven".