21161940 has 48 divisors (see below), whose sum is σ = 62741952. Its totient is φ = 5310976.

The previous prime is 21161939. The next prime is 21161941. The reversal of 21161940 is 4916112.

It is an interprime number because it is at equal distance from previous prime (21161939) and next prime (21161941).

It is a self number, because there is not a number n which added to its sum of digits gives 21161940.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21161941) 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 15 ways as a sum of consecutive naturals, for example, 9354 + ... + 11393.

It is an arithmetic number, because the mean of its divisors is an integer number (1307124).

Almost surely, 2^21161940 is an apocalyptic number.

21161940 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21161940 is an abundant number, since it is smaller than the sum of its proper divisors (41580012).

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

21161940 is a wasteful number, since it uses less digits than its factorization.

21161940 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20776 (or 20774 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 24.

The square root of 21161940 is about 4600.2108647322. The cubic root of 21161940 is about 276.5997773813.

The spelling of 21161940 in words is "twenty-one million, one hundred sixty-one thousand, nine hundred forty".