21956380 has 12 divisors (see below), whose sum is σ = 46108440. Its totient is φ = 8782544.

The previous prime is 21956351. The next prime is 21956399. The reversal of 21956380 is 8365912.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 548890 + ... + 548929.

It is an arithmetic number, because the mean of its divisors is an integer number (3842370).

Almost surely, 2^21956380 is an apocalyptic number.

21956380 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21956380 is an abundant number, since it is smaller than the sum of its proper divisors (24152060).

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

21956380 is a wasteful number, since it uses less digits than its factorization.

21956380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1097828 (or 1097826 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 34.

The square root of 21956380 is about 4685.7635450372. The cubic root of 21956380 is about 280.0186212106.

The spelling of 21956380 in words is "twenty-one million, nine hundred fifty-six thousand, three hundred eighty".