21678135740 has 36 divisors (see below), whose sum is σ = 45696691656. Its totient is φ = 8638409376.

The previous prime is 21678135673. The next prime is 21678135749. The reversal of 21678135740 is 4753187612.

It is a junction number, because it is equal to n+sod(n) for n = 21678135691 and 21678135700.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21678135749) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11536121 + ... + 11537999.

It is an arithmetic number, because the mean of its divisors is an integer number (1269352546).

Almost surely, 2^21678135740 is an apocalyptic number.

21678135740 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21678135740 is an abundant number, since it is smaller than the sum of its proper divisors (24018555916).

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

21678135740 is an equidigital number, since it uses as much as digits as its factorization.

21678135740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4074 (or 2193 counting only the distinct ones).

The product of its (nonzero) digits is 282240, while the sum is 44.

The spelling of 21678135740 in words is "twenty-one billion, six hundred seventy-eight million, one hundred thirty-five thousand, seven hundred forty".