21551351712 has 96 divisors (see below), whose sum is σ = 61752305664. Its totient is φ = 6526790400.

The previous prime is 21551351699. The next prime is 21551351713. The reversal of 21551351712 is 21715315512.

It is a tau number, because it is divible by the number of its divisors (96).

It is a super-2 number, since 2×21551351712² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is not an unprimeable number, because it can be changed into a prime (21551351713) 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, 2093137 + ... + 2103407.

It is an arithmetic number, because the mean of its divisors is an integer number (643253184).

Almost surely, 2^21551351712 is an apocalyptic number.

21551351712 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21551351712, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30876152832).

21551351712 is an abundant number, since it is smaller than the sum of its proper divisors (40200953952).

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

21551351712 is a wasteful number, since it uses less digits than its factorization.

21551351712 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12282 (or 12274 counting only the distinct ones).

The product of its digits is 10500, while the sum is 33.

The spelling of 21551351712 in words is "twenty-one billion, five hundred fifty-one million, three hundred fifty-one thousand, seven hundred twelve".