1561501889 has 4 divisors (see below), whose sum is σ = 1562188740. Its totient is φ = 1560815040.

The previous prime is 1561501859. The next prime is 1561501927. The reversal of 1561501889 is 9881051651.

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 853516225 + 707985664 = 29215^2 + 26608^2 .

It is a cyclic number.

It is not a de Polignac number, because 1561501889 - 2¹² = 1561497793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1561501849) 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, 340004 + ... + 344565.

It is an arithmetic number, because the mean of its divisors is an integer number (390547185).

Almost surely, 2^1561501889 is an apocalyptic number.

It is an amenable number.

1561501889 is a deficient number, since it is larger than the sum of its proper divisors (686851).

1561501889 is an equidigital number, since it uses as much as digits as its factorization.

1561501889 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 686850.

The product of its (nonzero) digits is 86400, while the sum is 44.

The square root of 1561501889 is about 39515.8435187711. The cubic root of 1561501889 is about 1160.1500719930.

The spelling of 1561501889 in words is "one billion, five hundred sixty-one million, five hundred one thousand, eight hundred eighty-nine".