1551561 has 8 divisors (see below), whose sum is σ = 2256864. Its totient is φ = 940320.

The previous prime is 1551551. The next prime is 1551577. The reversal of 1551561 is 1651551.

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

It is not a de Polignac number, because 1551561 - 2⁶ = 1551497 is a prime.

It is a Smith number, since the sum of its digits (24) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (1551551) 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, 23476 + ... + 23541.

It is an arithmetic number, because the mean of its divisors is an integer number (282108).

2^1551561 is an apocalyptic number.

1551561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1551561 is a deficient number, since it is larger than the sum of its proper divisors (705303).

1551561 is a wasteful number, since it uses less digits than its factorization.

1551561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47031.

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

The square root of 1551561 is about 1245.6167147241. The cubic root of 1551561 is about 115.7682899444.

It can be divided in two parts, 15515 and 61, that added together give a triangular number (15576 = T₁₇₆).

The spelling of 1551561 in words is "one million, five hundred fifty-one thousand, five hundred sixty-one".