21920340 has 96 divisors (see below), whose sum is σ = 66890880. Its totient is φ = 5331456.

The previous prime is 21920321. The next prime is 21920359. The reversal of 21920340 is 4302912.

It is an interprime number because it is at equal distance from previous prime (21920321) and next prime (21920359).

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 31 ways as a sum of consecutive naturals, for example, 122371 + ... + 122549.

It is an arithmetic number, because the mean of its divisors is an integer number (696780).

Almost surely, 2^21920340 is an apocalyptic number.

21920340 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21920340, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33445440).

21920340 is an abundant number, since it is smaller than the sum of its proper divisors (44970540).

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

21920340 is a wasteful number, since it uses less digits than its factorization.

21920340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 361 (or 359 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 21.

The square root of 21920340 is about 4681.9162743475. The cubic root of 21920340 is about 279.8653263919.

The spelling of 21920340 in words is "twenty-one million, nine hundred twenty thousand, three hundred forty".