21930381 has 24 divisors (see below), whose sum is σ = 35496864. Its totient is φ = 12929760.

The previous prime is 21930379. The next prime is 21930383. The reversal of 21930381 is 18303912.

It is an interprime number because it is at equal distance from previous prime (21930379) and next prime (21930383).

It is not a de Polignac number, because 21930381 - 2¹ = 21930379 is a prime.

It is a super-2 number, since 2×21930381² = 961883221610322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21930383) 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, 670 + ... + 6656.

It is an arithmetic number, because the mean of its divisors is an integer number (1479036).

Almost surely, 2^21930381 is an apocalyptic number.

It is an amenable number.

21930381 is a deficient number, since it is larger than the sum of its proper divisors (13566483).

21930381 is a wasteful number, since it uses less digits than its factorization.

21930381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6041 (or 6038 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The square root of 21930381 is about 4682.9884689160. The cubic root of 21930381 is about 279.9080522921.

The spelling of 21930381 in words is "twenty-one million, nine hundred thirty thousand, three hundred eighty-one".