21120381 has 24 divisors (see below), whose sum is σ = 33228000. Its totient is φ = 12876192.

The previous prime is 21120367. The next prime is 21120383. The reversal of 21120381 is 18302112.

It is not a de Polignac number, because 21120381 - 2⁵ = 21120349 is a prime.

It is a super-2 number, since 2×21120381² = 892140987170322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21120383) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2830 + ... + 7088.

It is an arithmetic number, because the mean of its divisors is an integer number (1384500).

Almost surely, 2^21120381 is an apocalyptic number.

It is an amenable number.

21120381 is a deficient number, since it is larger than the sum of its proper divisors (12107619).

21120381 is a wasteful number, since it uses less digits than its factorization.

21120381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4313 (or 4310 counting only the distinct ones).

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

The square root of 21120381 is about 4595.6915692853. The cubic root of 21120381 is about 276.4185913566.

Adding to 21120381 its reverse (18302112), we get a palindrome (39422493).

The spelling of 21120381 in words is "twenty-one million, one hundred twenty thousand, three hundred eighty-one".