21127686840 has 640 divisors, whose sum is σ = 80923328640. Its totient is φ = 4904976384.

The previous prime is 21127686829. The next prime is 21127686859. The reversal of 21127686840 is 4868672112.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 109469784 + ... + 109469976.

It is an arithmetic number, because the mean of its divisors is an integer number (126442701).

Almost surely, 2^21127686840 is an apocalyptic number.

21127686840 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 21127686840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40461664320).

21127686840 is an abundant number, since it is smaller than the sum of its proper divisors (59795641800).

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

21127686840 is a wasteful number, since it uses less digits than its factorization.

21127686840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 365 (or 352 counting only the distinct ones).

The product of its (nonzero) digits is 258048, while the sum is 45.

It can be divided in two parts, 211276 and 86840, that added together give a square (298116 = 546²).

The spelling of 21127686840 in words is "twenty-one billion, one hundred twenty-seven million, six hundred eighty-six thousand, eight hundred forty".