21729239620 has 48 divisors (see below), whose sum is σ = 49986389376. Its totient is φ = 7868736000.

The previous prime is 21729239611. The next prime is 21729239621. The reversal of 21729239620 is 2693292712.

It is a Smith number, since the sum of its digits (43) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (21729239621) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 151896 + ... + 257935.

It is an arithmetic number, because the mean of its divisors is an integer number (1041383112).

Almost surely, 2^21729239620 is an apocalyptic number.

21729239620 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21729239620 is an abundant number, since it is smaller than the sum of its proper divisors (28257149756).

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

21729239620 is a wasteful number, since it uses less digits than its factorization.

21729239620 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 410092 (or 410090 counting only the distinct ones).

The product of its (nonzero) digits is 163296, while the sum is 43.

The spelling of 21729239620 in words is "twenty-one billion, seven hundred twenty-nine million, two hundred thirty-nine thousand, six hundred twenty".