21655212632340 has 192 divisors, whose sum is σ = 69894623361024. Its totient is φ = 4907230336512.

The previous prime is 21655212632309. The next prime is 21655212632351. The reversal of 21655212632340 is 4323621255612.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a junction number, because it is equal to n+sod(n) for n = 21655212632292 and 21655212632301.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 22953007 + ... + 23877833.

It is an arithmetic number, because the mean of its divisors is an integer number (364034496672).

Almost surely, 2^{21655212632340} is an apocalyptic number.

21655212632340 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 21655212632340, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34947311680512).

21655212632340 is an abundant number, since it is smaller than the sum of its proper divisors (48239410728684).

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

21655212632340 is a wasteful number, since it uses less digits than its factorization.

21655212632340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 925326 (or 925324 counting only the distinct ones).

The product of its (nonzero) digits is 518400, while the sum is 42.

Adding to 21655212632340 its reverse (4323621255612), we get a palindrome (25978833887952).

The spelling of 21655212632340 in words is "twenty-one trillion, six hundred fifty-five billion, two hundred twelve million, six hundred thirty-two thousand, three hundred forty".