351561 has 8 divisors (see below), whose sum is σ = 535744. Its totient is φ = 200880.

The previous prime is 351551. The next prime is 351563. The reversal of 351561 is 165153.

It is a happy number.

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

It is not a de Polignac number, because 351561 - 2⁵ = 351529 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21), and also a Moran number because the ratio is a prime number: 16741 = 351561 / (3 + 5 + 1 + 5 + 6 + 1).

It is an Ulam number.

It is a Duffinian number.

It is a Curzon number.

351561 is a lucky number.

It is a nialpdrome in base 5.

It is not an unprimeable number, because it can be changed into a prime (351563) 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, 8350 + ... + 8391.

It is an arithmetic number, because the mean of its divisors is an integer number (66968).

2³⁵¹⁵⁶¹ is an apocalyptic number.

It is an amenable number.

351561 is a deficient number, since it is larger than the sum of its proper divisors (184183).

351561 is a wasteful number, since it uses less digits than its factorization.

351561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16751.

The product of its digits is 450, while the sum is 21.

The square root of 351561 is about 592.9257963692. The cubic root of 351561 is about 70.5776017888.

It can be divided in two parts, 35 and 1561, that added together give a triangular number (1596 = T₅₆).

The spelling of 351561 in words is "three hundred fifty-one thousand, five hundred sixty-one".