21946840 has 16 divisors (see below), whose sum is σ = 49380480. Its totient is φ = 8778720.

The previous prime is 21946831. The next prime is 21946867. The reversal of 21946840 is 4864912.

It is a junction number, because it is equal to n+sod(n) for n = 21946796 and 21946805.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 274296 + ... + 274375.

It is an arithmetic number, because the mean of its divisors is an integer number (3086280).

Almost surely, 2^21946840 is an apocalyptic number.

21946840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21946840 is an abundant number, since it is smaller than the sum of its proper divisors (27433640).

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

21946840 is a wasteful number, since it uses less digits than its factorization.

21946840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 548682 (or 548678 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 34.

The square root of 21946840 is about 4684.7454573328. The cubic root of 21946840 is about 279.9780595053.

The spelling of 21946840 in words is "twenty-one million, nine hundred forty-six thousand, eight hundred forty".