1561172401 has 4 divisors (see below), whose sum is σ = 1569097332. Its totient is φ = 1553247472.

The previous prime is 1561172381. The next prime is 1561172419. The reversal of 1561172401 is 1042711651.

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

It can be written as a sum of positive squares in 2 ways, for example, as 755975025 + 805197376 = 27495^2 + 28376^2 .

It is a cyclic number.

It is not a de Polignac number, because 1561172401 - 2¹¹ = 1561170353 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 1561172401.

It is not an unprimeable number, because it can be changed into a prime (1561172201) 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, 3962170 + ... + 3962563.

It is an arithmetic number, because the mean of its divisors is an integer number (392274333).

Almost surely, 2^1561172401 is an apocalyptic number.

It is an amenable number.

1561172401 is a deficient number, since it is larger than the sum of its proper divisors (7924931).

1561172401 is an equidigital number, since it uses as much as digits as its factorization.

1561172401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7924930.

The product of its (nonzero) digits is 1680, while the sum is 28.

The square root of 1561172401 is about 39511.6742368632. The cubic root of 1561172401 is about 1160.0684662819.

The spelling of 1561172401 in words is "one billion, five hundred sixty-one million, one hundred seventy-two thousand, four hundred one".