21141981 has 36 divisors (see below), whose sum is σ = 35852544. Its totient is φ = 11970000.

The previous prime is 21141973. The next prime is 21142021. The reversal of 21141981 is 18914112.

It is not a de Polignac number, because 21141981 - 2³ = 21141973 is a prime.

It is a super-2 number, since 2×21141981² = 893966721208722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21141941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 84106 + ... + 84356.

It is an arithmetic number, because the mean of its divisors is an integer number (995904).

Almost surely, 2^21141981 is an apocalyptic number.

21141981 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21141981 is a deficient number, since it is larger than the sum of its proper divisors (14710563).

21141981 is a wasteful number, since it uses less digits than its factorization.

21141981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 462 (or 452 counting only the distinct ones).

The product of its digits is 576, while the sum is 27.

The square root of 21141981 is about 4598.0409959025. The cubic root of 21141981 is about 276.5127911617.

It can be divided in two parts, 21141 and 981, that added together give a palindrome (22122).

The spelling of 21141981 in words is "twenty-one million, one hundred forty-one thousand, nine hundred eighty-one".