20867561 has 16 divisors (see below), whose sum is σ = 24864000. Its totient is φ = 17262720.

The previous prime is 20867543. The next prime is 20867573. The reversal of 20867561 is 16576802.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20867561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20867521) 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, 9440 + ... + 11438.

It is an arithmetic number, because the mean of its divisors is an integer number (1554000).

Almost surely, 2^20867561 is an apocalyptic number.

It is an amenable number.

20867561 is a deficient number, since it is larger than the sum of its proper divisors (3996439).

20867561 is a wasteful number, since it uses less digits than its factorization.

20867561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2096.

The product of its (nonzero) digits is 20160, while the sum is 35.

The square root of 20867561 is about 4568.1025601446. The cubic root of 20867561 is about 275.3112113127.

The spelling of 20867561 in words is "twenty million, eight hundred sixty-seven thousand, five hundred sixty-one".