20291221440 has 896 divisors, whose sum is σ = 86026752000. Its totient is φ = 4497776640.

The previous prime is 20291221429. The next prime is 20291221501. The reversal of 20291221440 is 4412219202.

20291221440 is a `hidden beast` number, since 202 + 9 + 12 + 2 + 1 + 440 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 121504237 + ... + 121504403.

It is an arithmetic number, because the mean of its divisors is an integer number (96012000).

Almost surely, 2^20291221440 is an apocalyptic number.

20291221440 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 20291221440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43013376000).

20291221440 is an abundant number, since it is smaller than the sum of its proper divisors (65735530560).

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

20291221440 is a wasteful number, since it uses less digits than its factorization.

20291221440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 255 (or 225 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The spelling of 20291221440 in words is "twenty billion, two hundred ninety-one million, two hundred twenty-one thousand, four hundred forty".