20721960 has 128 divisors (see below), whose sum is σ = 78969600. Its totient is φ = 4734720.

The previous prime is 20721949. The next prime is 20721983. The reversal of 20721960 is 6912702.

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

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 6190 + ... + 8930.

It is an arithmetic number, because the mean of its divisors is an integer number (616950).

Almost surely, 2^20721960 is an apocalyptic number.

20721960 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 20721960, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39484800).

20721960 is an abundant number, since it is smaller than the sum of its proper divisors (58247640).

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

20721960 is a wasteful number, since it uses less digits than its factorization.

20721960 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2768 (or 2758 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 27.

The square root of 20721960 is about 4552.1379592451. The cubic root of 20721960 is about 274.6693988585.

The spelling of 20721960 in words is "twenty million, seven hundred twenty-one thousand, nine hundred sixty".