21135228717880 has 64 divisors (see below), whose sum is σ = 47810926369440. Its totient is φ = 8408536300032.

The previous prime is 21135228717877. The next prime is 21135228717881. The reversal of 21135228717880 is 8871782253112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21135228717881) 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, 8049142 + ... + 10346938.

Almost surely, 2^{21135228717880} is an apocalyptic number.

21135228717880 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21135228717880 is an abundant number, since it is smaller than the sum of its proper divisors (26675697651560).

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

21135228717880 is a wasteful number, since it uses less digits than its factorization.

21135228717880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2299048 (or 2299044 counting only the distinct ones).

The product of its (nonzero) digits is 3010560, while the sum is 55.

The spelling of 21135228717880 in words is "twenty-one trillion, one hundred thirty-five billion, two hundred twenty-eight million, seven hundred seventeen thousand, eight hundred eighty".