1221381 has 12 divisors (see below), whose sum is σ = 2016352. Its totient is φ = 697896.

The previous prime is 1221379. The next prime is 1221383. The reversal of 1221381 is 1831221.

It is an interprime number because it is at equal distance from previous prime (1221379) and next prime (1221383).

It is not a de Polignac number, because 1221381 - 2¹ = 1221379 is a prime.

It is a super-2 number, since 2×1221381² = 2983543094322, which contains 22 as substring.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221383) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9631 + ... + 9756.

2^1221381 is an apocalyptic number.

It is an amenable number.

1221381 is a deficient number, since it is larger than the sum of its proper divisors (794971).

1221381 is a wasteful number, since it uses less digits than its factorization.

1221381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19400 (or 19397 counting only the distinct ones).

The product of its digits is 96, while the sum is 18.

The square root of 1221381 is about 1105.1610742331. The cubic root of 1221381 is about 106.8932758322.

The spelling of 1221381 in words is "one million, two hundred twenty-one thousand, three hundred eighty-one".