1661631 has 16 divisors (see below), whose sum is σ = 2423808. Its totient is φ = 1008000.

The previous prime is 1661629. The next prime is 1661641. The reversal of 1661631 is 1361661.

It is not a de Polignac number, because 1661631 - 2¹ = 1661629 is a prime.

It is a super-2 number, since 2×1661631² = 5522035160322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661641) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1056 + ... + 2106.

It is an arithmetic number, because the mean of its divisors is an integer number (151488).

2^1661631 is an apocalyptic number.

1661631 is a deficient number, since it is larger than the sum of its proper divisors (762177).

1661631 is a wasteful number, since it uses less digits than its factorization.

1661631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1102.

The product of its digits is 648, while the sum is 24.

The square root of 1661631 is about 1289.0426680293. The cubic root of 1661631 is about 118.4435808264.

The spelling of 1661631 in words is "one million, six hundred sixty-one thousand, six hundred thirty-one".