20504721 has 8 divisors (see below), whose sum is σ = 27364480. Its totient is φ = 13657392.

The previous prime is 20504719. The next prime is 20504741. The reversal of 20504721 is 12740502.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20504721 - 2¹ = 20504719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20504741) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1896 + ... + 6678.

It is an arithmetic number, because the mean of its divisors is an integer number (3420560).

Almost surely, 2^20504721 is an apocalyptic number.

It is an amenable number.

20504721 is a deficient number, since it is larger than the sum of its proper divisors (6859759).

20504721 is a wasteful number, since it uses less digits than its factorization.

20504721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6215.

The product of its (nonzero) digits is 560, while the sum is 21.

The square root of 20504721 is about 4528.2138862912. The cubic root of 20504721 is about 273.7061913591.

The spelling of 20504721 in words is "twenty million, five hundred four thousand, seven hundred twenty-one".