1866381 has 16 divisors (see below), whose sum is σ = 2833920. Its totient is φ = 1081520.

The previous prime is 1866373. The next prime is 1866409. The reversal of 1866381 is 1836681.

It is not a de Polignac number, because 1866381 - 2³ = 1866373 is a prime.

It is a super-2 number, since 2×1866381² = 6966756074322, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1866301) 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, 471 + ... + 1988.

It is an arithmetic number, because the mean of its divisors is an integer number (177120).

2^1866381 is an apocalyptic number.

1866381 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1866381 is a deficient number, since it is larger than the sum of its proper divisors (967539).

1866381 is a wasteful number, since it uses less digits than its factorization.

1866381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2496.

The product of its digits is 6912, while the sum is 33.

The square root of 1866381 is about 1366.1555548326. The cubic root of 1866381 is about 123.1213687335.

The spelling of 1866381 in words is "one million, eight hundred sixty-six thousand, three hundred eighty-one".