1661377 has 4 divisors (see below), whose sum is σ = 1663956. Its totient is φ = 1658800.

The previous prime is 1661353. The next prime is 1661431. The reversal of 1661377 is 7731661.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 370881 + 1290496 = 609^2 + 1136^2 .

It is a cyclic number.

It is not a de Polignac number, because 1661377 - 2⁷ = 1661249 is a prime.

It is a super-2 number, since 2×1661377² = 5520347072258, which contains 22 as substring.

It is a Duffinian number.

1661377 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (1661327) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 627 + ... + 1927.

It is an arithmetic number, because the mean of its divisors is an integer number (415989).

2^1661377 is an apocalyptic number.

It is an amenable number.

1661377 is a deficient number, since it is larger than the sum of its proper divisors (2579).

1661377 is a wasteful number, since it uses less digits than its factorization.

1661377 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2578.

The product of its digits is 5292, while the sum is 31.

The square root of 1661377 is about 1288.9441415360. The cubic root of 1661377 is about 118.4375453503.

The spelling of 1661377 in words is "one million, six hundred sixty-one thousand, three hundred seventy-seven".