20960721 has 16 divisors (see below), whose sum is σ = 31233600. Its totient is φ = 13892544.

The previous prime is 20960713. The next prime is 20960729. The reversal of 20960721 is 12706902.

It is an interprime number because it is at equal distance from previous prime (20960713) and next prime (20960729).

It is not a de Polignac number, because 20960721 - 2³ = 20960713 is a prime.

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

It is not an unprimeable number, because it can be changed into a prime (20960729) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2665 + ... + 7001.

It is an arithmetic number, because the mean of its divisors is an integer number (1952100).

Almost surely, 2^20960721 is an apocalyptic number.

It is an amenable number.

20960721 is a deficient number, since it is larger than the sum of its proper divisors (10272879).

20960721 is a wasteful number, since it uses less digits than its factorization.

20960721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4525 (or 4519 counting only the distinct ones).

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

The square root of 20960721 is about 4578.2879988048. The cubic root of 20960721 is about 275.7202979274.

It can be divided in two parts, 209607 and 21, that added together give a triangular number (209628 = T₆₄₇).

The spelling of 20960721 in words is "twenty million, nine hundred sixty thousand, seven hundred twenty-one".