21021255984 has 40 divisors (see below), whose sum is σ = 56177498160. Its totient is φ = 6765461248.

The previous prime is 21021255979. The next prime is 21021255991. The reversal of 21021255984 is 48955212012.

It is a super-3 number, since 3×21021255984³ (a number of 32 digits) contains 333 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7549347 + ... + 7552130.

It is an arithmetic number, because the mean of its divisors is an integer number (1404437454).

Almost surely, 2^21021255984 is an apocalyptic number.

21021255984 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21021255984 is an abundant number, since it is smaller than the sum of its proper divisors (35156242176).

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

21021255984 is a wasteful number, since it uses less digits than its factorization.

21021255984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15101517 (or 15101511 counting only the distinct ones).

The product of its (nonzero) digits is 57600, while the sum is 39.

Adding to 21021255984 its reverse (48955212012), we get a palindrome (69976467996).

The spelling of 21021255984 in words is "twenty-one billion, twenty-one million, two hundred fifty-five thousand, nine hundred eighty-four".