20291880 has 256 divisors, whose sum is σ = 77760000. Its totient is φ = 4214784.

The previous prime is 20291879. The next prime is 20291893. The reversal of 20291880 is 8819202.

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 polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 699706 + ... + 699734.

It is an arithmetic number, because the mean of its divisors is an integer number (303750).

Almost surely, 2^20291880 is an apocalyptic number.

20291880 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 20291880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38880000).

20291880 is an abundant number, since it is smaller than the sum of its proper divisors (57468120).

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

20291880 is a wasteful number, since it uses less digits than its factorization.

20291880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81 (or 63 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 30.

The square root of 20291880 is about 4504.6509298724. The cubic root of 20291880 is about 272.7558632653.

The spelling of 20291880 in words is "twenty million, two hundred ninety-one thousand, eight hundred eighty".