21961286072 has 48 divisors (see below), whose sum is σ = 45310807080. Its totient is φ = 9971445440.

The previous prime is 21961286057. The next prime is 21961286099. The reversal of 21961286072 is 27068216912.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (44).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 904718 + ... + 928674.

Almost surely, 2^21961286072 is an apocalyptic number.

21961286072 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 21961286072, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22655403540).

21961286072 is an abundant number, since it is smaller than the sum of its proper divisors (23349521008).

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

21961286072 is a wasteful number, since it uses less digits than its factorization.

21961286072 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24932 (or 24917 counting only the distinct ones).

The product of its (nonzero) digits is 145152, while the sum is 44.

The spelling of 21961286072 in words is "twenty-one billion, nine hundred sixty-one million, two hundred eighty-six thousand, seventy-two".