1661216 has 12 divisors (see below), whose sum is σ = 3270582. Its totient is φ = 830592.

The previous prime is 1661173. The next prime is 1661237. The reversal of 1661216 is 6121661.

It can be written as a sum of positive squares in only one way, i.e., 1449616 + 211600 = 1204^2 + 460^2 .

It is a junction number, because it is equal to n+sod(n) for n = 1661191 and 1661200.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25925 + ... + 25988.

2^1661216 is an apocalyptic number.

1661216 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

1661216 is a deficient number, since it is larger than the sum of its proper divisors (1609366).

1661216 is an equidigital number, since it uses as much as digits as its factorization.

1661216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51923 (or 51915 counting only the distinct ones).

The product of its digits is 432, while the sum is 23.

The square root of 1661216 is about 1288.8816858036. The cubic root of 1661216 is about 118.4337193953.

Adding to 1661216 its reverse (6121661), we get a palindrome (7782877).

The spelling of 1661216 in words is "one million, six hundred sixty-one thousand, two hundred sixteen".