16381021 has 4 divisors (see below), whose sum is σ = 17243200. Its totient is φ = 15518844.

The previous prime is 16381007. The next prime is 16381033. The reversal of 16381021 is 12018361.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12018361 = 563 ⋅21347.

It is a cyclic number.

It is not a de Polignac number, because 16381021 - 2⁹ = 16380509 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 16380983 and 16381001.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16381061) 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, 431061 + ... + 431098.

It is an arithmetic number, because the mean of its divisors is an integer number (4310800).

Almost surely, 2^16381021 is an apocalyptic number.

It is an amenable number.

16381021 is a deficient number, since it is larger than the sum of its proper divisors (862179).

16381021 is an equidigital number, since it uses as much as digits as its factorization.

16381021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 862178.

The product of its (nonzero) digits is 288, while the sum is 22.

The square root of 16381021 is about 4047.3474029295. The cubic root of 16381021 is about 253.9687739322.

Adding to 16381021 its reverse (12018361), we get a palindrome (28399382).

The spelling of 16381021 in words is "sixteen million, three hundred eighty-one thousand, twenty-one".