21221199972 has 144 divisors (see below), whose sum is σ = 62204222080. Its totient is φ = 5974953984.

The previous prime is 21221199949. The next prime is 21221199973. The reversal of 21221199972 is 27999112212.

It is a super-2 number, since 2×21221199972² (a number of 21 digits) contains 22 as substring.

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (21221199973) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 5299323 + ... + 5303325.

Almost surely, 2^21221199972 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 21221199972, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31102111040).

21221199972 is an abundant number, since it is smaller than the sum of its proper divisors (40983022108).

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

21221199972 is a wasteful number, since it uses less digits than its factorization.

21221199972 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4322 (or 4317 counting only the distinct ones).

The product of its digits is 81648, while the sum is 45.

The spelling of 21221199972 in words is "twenty-one billion, two hundred twenty-one million, one hundred ninety-nine thousand, nine hundred seventy-two".