21129985501872 has 80 divisors (see below), whose sum is σ = 58838000460288. Its totient is φ = 6495639379200.

The previous prime is 21129985501871. The next prime is 21129985501873. The reversal of 21129985501872 is 27810558992112.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21129985501871) and next prime (21129985501873).

It is a super-3 number, since 3×21129985501872³ (a number of 41 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (21129985501871) 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, 14661754 + ... + 16038297.

Almost surely, 2^{21129985501872} is an apocalyptic number.

It is an amenable number.

21129985501872 is an abundant number, since it is smaller than the sum of its proper divisors (37708014958416).

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

21129985501872 is a wasteful number, since it uses less digits than its factorization.

21129985501872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30701178 (or 30701172 counting only the distinct ones).

The product of its (nonzero) digits is 7257600, while the sum is 60.

The spelling of 21129985501872 in words is "twenty-one trillion, one hundred twenty-nine billion, nine hundred eighty-five million, five hundred one thousand, eight hundred seventy-two".