21123840528 has 80 divisors (see below), whose sum is σ = 69295148160. Its totient is φ = 6035382144.

The previous prime is 21123840511. The next prime is 21123840581. The reversal of 21123840528 is 82504832112.

It is a happy number.

21123840528 is a `hidden beast` number, since 2 + 1 + 123 + 8 + 4 + 0 + 528 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21123840492 and 21123840501.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3489675 + ... + 3495722.

It is an arithmetic number, because the mean of its divisors is an integer number (866189352).

Almost surely, 2^21123840528 is an apocalyptic number.

21123840528 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21123840528 is an abundant number, since it is smaller than the sum of its proper divisors (48171307632).

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

21123840528 is a wasteful number, since it uses less digits than its factorization.

21123840528 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6985421 (or 6985409 counting only the distinct ones).

The product of its (nonzero) digits is 30720, while the sum is 36.

The spelling of 21123840528 in words is "twenty-one billion, one hundred twenty-three million, eight hundred forty thousand, five hundred twenty-eight".