1561366 has 4 divisors (see below), whose sum is σ = 2342052. Its totient is φ = 780682.

The previous prime is 1561349. The next prime is 1561367. The reversal of 1561366 is 6631651.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 6631651 = 13 ⋅510127.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1561367) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 390340 + ... + 390343.

It is an arithmetic number, because the mean of its divisors is an integer number (585513).

2^1561366 is an apocalyptic number.

1561366 is a deficient number, since it is larger than the sum of its proper divisors (780686).

1561366 is an equidigital number, since it uses as much as digits as its factorization.

1561366 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 780685.

The product of its digits is 3240, while the sum is 28.

The square root of 1561366 is about 1249.5463176689. The cubic root of 1561366 is about 116.0116417171.

The spelling of 1561366 in words is "one million, five hundred sixty-one thousand, three hundred sixty-six".