3551220 has 72 divisors (see below), whose sum is σ = 10930920. Its totient is φ = 933120.

The previous prime is 3551213. The next prime is 3551221. The reversal of 3551220 is 221553.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 24336 + 3526884 = 156^2 + 1878^2 .

It is a super-2 number, since 2×3551220² = 25222326976800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 3551193 and 3551202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3551221) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 19530 + ... + 19710.

Almost surely, 2^3551220 is an apocalyptic number.

3551220 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 3551220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (5465460).

3551220 is an abundant number, since it is smaller than the sum of its proper divisors (7379700).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

3551220 is a wasteful number, since it uses less digits than its factorization.

3551220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 305 (or 300 counting only the distinct ones).

The product of its (nonzero) digits is 300, while the sum is 18.

The square root of 3551220 is about 1884.4680947153. The cubic root of 3551220 is about 152.5665032887.

Adding to 3551220 its reverse (221553), we get a palindrome (3772773).

The spelling of 3551220 in words is "three million, five hundred fifty-one thousand, two hundred twenty".