21001951512 has 96 divisors (see below), whose sum is σ = 59109785280. Its totient is φ = 6986075040.

The previous prime is 21001951501. The next prime is 21001951541. The reversal of 21001951512 is 21515910012.

It is a super-2 number, since 2×21001951512² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 943503 + ... + 965505.

It is an arithmetic number, because the mean of its divisors is an integer number (615726930).

Almost surely, 2^21001951512 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21001951512, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29554892640).

21001951512 is an abundant number, since it is smaller than the sum of its proper divisors (38107833768).

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

21001951512 is a wasteful number, since it uses less digits than its factorization.

21001951512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22515 (or 22499 counting only the distinct ones).

The product of its (nonzero) digits is 900, while the sum is 27.

The spelling of 21001951512 in words is "twenty-one billion, one million, nine hundred fifty-one thousand, five hundred twelve".