1561551 has 8 divisors (see below), whose sum is σ = 2092080. Its totient is φ = 1036032.

The previous prime is 1561541. The next prime is 1561559. The reversal of 1561551 is 1551651.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1561551 - 2⁵ = 1561519 is a prime.

1561551 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1561559) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 450 + ... + 1823.

It is an arithmetic number, because the mean of its divisors is an integer number (261510).

2^1561551 is an apocalyptic number.

1561551 is a deficient number, since it is larger than the sum of its proper divisors (530529).

1561551 is a wasteful number, since it uses less digits than its factorization.

1561551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2505.

The product of its digits is 750, while the sum is 24.

The square root of 1561551 is about 1249.6203423440. The cubic root of 1561551 is about 116.0162234543.

It can be divided in two parts, 1561 and 551, that added together give a palindrome (2112).

The spelling of 1561551 in words is "one million, five hundred sixty-one thousand, five hundred fifty-one".