21011982 has 8 divisors (see below), whose sum is σ = 42023976. Its totient is φ = 7003992.

The previous prime is 21011981. The next prime is 21012053. The reversal of 21011982 is 28911012.

It is a sphenic number, since it is the product of 3 distinct primes.

21011982 is an admirable number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011981) 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, 1750993 + ... + 1751004.

It is an arithmetic number, because the mean of its divisors is an integer number (5252997).

Almost surely, 2^21011982 is an apocalyptic number.

21011982 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21011982 is a wasteful number, since it uses less digits than its factorization.

21011982 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3502002.

The product of its (nonzero) digits is 288, while the sum is 24.

The square root of 21011982 is about 4583.8828519062. The cubic root of 21011982 is about 275.9448797719.

Adding to 21011982 its reverse (28911012), we get a palindrome (49922994).

The spelling of 21011982 in words is "twenty-one million, eleven thousand, nine hundred eighty-two".