20713721 has 12 divisors (see below), whose sum is σ = 24405120. Its totient is φ = 17526600.

The previous prime is 20713703. The next prime is 20713741. The reversal of 20713721 is 12731702.

It is not a de Polignac number, because 20713721 - 2⁶ = 20713657 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20713741) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1196 + ... + 6546.

It is an arithmetic number, because the mean of its divisors is an integer number (2033760).

Almost surely, 2^20713721 is an apocalyptic number.

It is an amenable number.

20713721 is a deficient number, since it is larger than the sum of its proper divisors (3691399).

20713721 is an equidigital number, since it uses as much as digits as its factorization.

20713721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5444 (or 5437 counting only the distinct ones).

The product of its (nonzero) digits is 588, while the sum is 23.

The square root of 20713721 is about 4551.2329098828. The cubic root of 20713721 is about 274.6329914085.

The spelling of 20713721 in words is "twenty million, seven hundred thirteen thousand, seven hundred twenty-one".