21098727720 has 576 divisors, whose sum is σ = 85448563200. Its totient is φ = 4663733760.

The previous prime is 21098727719. The next prime is 21098727721. The reversal of 21098727720 is 2772789012.

It is an interprime number because it is at equal distance from previous prime (21098727719) and next prime (21098727721).

It is a super-2 number, since 2×21098727720² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (21098727721) by changing a digit.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 14763966 + ... + 14765394.

It is an arithmetic number, because the mean of its divisors is an integer number (148348200).

Almost surely, 2^21098727720 is an apocalyptic number.

21098727720 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 21098727720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42724281600).

21098727720 is an abundant number, since it is smaller than the sum of its proper divisors (64349835480).

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

21098727720 is a wasteful number, since it uses less digits than its factorization.

21098727720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1500 (or 1477 counting only the distinct ones).

The product of its (nonzero) digits is 197568, while the sum is 45.

The spelling of 21098727720 in words is "twenty-one billion, ninety-eight million, seven hundred twenty-seven thousand, seven hundred twenty".