21910020 has 96 divisors (see below), whose sum is σ = 67858560. Its totient is φ = 5237760.

The previous prime is 21910013. The next prime is 21910043. The reversal of 21910020 is 2001912.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 58554 + ... + 58926.

It is an arithmetic number, because the mean of its divisors is an integer number (706860).

Almost surely, 2^21910020 is an apocalyptic number.

21910020 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 21910020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33929280).

21910020 is an abundant number, since it is smaller than the sum of its proper divisors (45948540).

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

21910020 is a wasteful number, since it uses less digits than its factorization.

21910020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 485 (or 483 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 15.

The square root of 21910020 is about 4680.8140317684. The cubic root of 21910020 is about 279.8213997080.

Adding to 21910020 its reverse (2001912), we get a palindrome (23911932).

The spelling of 21910020 in words is "twenty-one million, nine hundred ten thousand, twenty".