21081942 has 24 divisors (see below), whose sum is σ = 52203216. Its totient is φ = 6023376.

The previous prime is 21081941. The next prime is 21081943. The reversal of 21081942 is 24918012.

It is an interprime number because it is at equal distance from previous prime (21081941) and next prime (21081943).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21081941) 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 11 ways as a sum of consecutive naturals, for example, 83533 + ... + 83784.

It is an arithmetic number, because the mean of its divisors is an integer number (2175134).

Almost surely, 2^21081942 is an apocalyptic number.

21081942 is an abundant number, since it is smaller than the sum of its proper divisors (31121274).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21081942 is a wasteful number, since it uses less digits than its factorization.

21081942 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 167332 (or 167329 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 21081942 is about 4591.5075955507. The cubic root of 21081942 is about 276.2507959820.

Adding to 21081942 its reverse (24918012), we get a palindrome (45999954).

The spelling of 21081942 in words is "twenty-one million, eighty-one thousand, nine hundred forty-two".