1561961351 has 4 divisors (see below), whose sum is σ = 1562531472. Its totient is φ = 1561391232.

The previous prime is 1561961347. The next prime is 1561961383. The reversal of 1561961351 is 1531691651.

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

It is a cyclic number.

It is not a de Polignac number, because 1561961351 - 2² = 1561961347 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1561961311) 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, 280931 + ... + 286436.

It is an arithmetic number, because the mean of its divisors is an integer number (390632868).

Almost surely, 2^1561961351 is an apocalyptic number.

1561961351 is a deficient number, since it is larger than the sum of its proper divisors (570121).

1561961351 is an equidigital number, since it uses as much as digits as its factorization.

1561961351 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 570120.

The product of its digits is 24300, while the sum is 38.

The square root of 1561961351 is about 39521.6567339984. The cubic root of 1561961351 is about 1160.2638497611.

The spelling of 1561961351 in words is "one billion, five hundred sixty-one million, nine hundred sixty-one thousand, three hundred fifty-one".