21427969720 has 128 divisors (see below), whose sum is σ = 51257448000. Its totient is φ = 8039485440.

The previous prime is 21427969697. The next prime is 21427969721. The reversal of 21427969720 is 2796972412.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21427969721) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 57447454 + ... + 57447826.

Almost surely, 2^21427969720 is an apocalyptic number.

21427969720 is a gapful number since it is divisible by the number (20) 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 21427969720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25628724000).

21427969720 is an abundant number, since it is smaller than the sum of its proper divisors (29829478280).

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

21427969720 is a wasteful number, since it uses less digits than its factorization.

21427969720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 953 (or 949 counting only the distinct ones).

The product of its (nonzero) digits is 762048, while the sum is 49.

The spelling of 21427969720 in words is "twenty-one billion, four hundred twenty-seven million, nine hundred sixty-nine thousand, seven hundred twenty".