1661538 has 16 divisors (see below), whose sum is σ = 3430656. Its totient is φ = 535920.

The previous prime is 1661519. The next prime is 1661549. The reversal of 1661538 is 8351661.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4281 + ... + 4652.

It is an arithmetic number, because the mean of its divisors is an integer number (214416).

2^1661538 is an apocalyptic number.

1661538 is an abundant number, since it is smaller than the sum of its proper divisors (1769118).

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

1661538 is a wasteful number, since it uses less digits than its factorization.

1661538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8969.

The product of its digits is 4320, while the sum is 30.

The square root of 1661538 is about 1289.0065942422. The cubic root of 1661538 is about 118.4413710581.

It can be divided in two parts, 16615 and 38, that added together give a triangular number (16653 = T₁₈₂).

The spelling of 1661538 in words is "one million, six hundred sixty-one thousand, five hundred thirty-eight".