21290221920 has 384 divisors, whose sum is σ = 75873853440. Its totient is φ = 4973230080.

The previous prime is 21290221903. The next prime is 21290221957. The reversal of 21290221920 is 2912209212.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 17935567 + ... + 17936753.

It is an arithmetic number, because the mean of its divisors is an integer number (197588160).

Almost surely, 2^21290221920 is an apocalyptic number.

21290221920 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 21290221920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37936926720).

21290221920 is an abundant number, since it is smaller than the sum of its proper divisors (54583631520).

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

21290221920 is a wasteful number, since it uses less digits than its factorization.

21290221920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1338 (or 1330 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 30.

The spelling of 21290221920 in words is "twenty-one billion, two hundred ninety million, two hundred twenty-one thousand, nine hundred twenty".