20930561 has 4 divisors (see below), whose sum is σ = 20939712. Its totient is φ = 20921412.

The previous prime is 20930513. The next prime is 20930579. The reversal of 20930561 is 16503902.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 16503902 = 2 ⋅8251951.

It is a cyclic number.

It is not a de Polignac number, because 20930561 - 2¹⁰ = 20929537 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20930561.

It is not an unprimeable number, because it can be changed into a prime (20930501) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2276 + ... + 6858.

It is an arithmetic number, because the mean of its divisors is an integer number (5234928).

It is a Proth number, since it is equal to 2555 ⋅ 2¹³ + 1 and 2555 < 2¹³.

Almost surely, 2^20930561 is an apocalyptic number.

It is an amenable number.

20930561 is a deficient number, since it is larger than the sum of its proper divisors (9151).

20930561 is an equidigital number, since it uses as much as digits as its factorization.

20930561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9150.

The product of its (nonzero) digits is 1620, while the sum is 26.

The square root of 20930561 is about 4574.9930054591. The cubic root of 20930561 is about 275.5879914763.

The spelling of 20930561 in words is "twenty million, nine hundred thirty thousand, five hundred sixty-one".