21258070820 has 144 divisors (see below), whose sum is σ = 54855618048. Its totient is φ = 6888913920.

The previous prime is 21258070819. The next prime is 21258070829. The reversal of 21258070820 is 2807085212.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is not an unprimeable number, because it can be changed into a prime (21258070829) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1298204 + ... + 1314476.

It is an arithmetic number, because the mean of its divisors is an integer number (380941792).

Almost surely, 2^21258070820 is an apocalyptic number.

21258070820 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 21258070820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27427809024).

21258070820 is an abundant number, since it is smaller than the sum of its proper divisors (33597547228).

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

21258070820 is a wasteful number, since it uses less digits than its factorization.

21258070820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16370 (or 16361 counting only the distinct ones).

The product of its (nonzero) digits is 17920, while the sum is 35.

The spelling of 21258070820 in words is "twenty-one billion, two hundred fifty-eight million, seventy thousand, eight hundred twenty".