20611961 has 4 divisors (see below), whose sum is σ = 20949924. Its totient is φ = 20274000.

The previous prime is 20611951. The next prime is 20611967. The reversal of 20611961 is 16911602.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 640000 + 19971961 = 800^2 + 4469^2 .

It is a cyclic number.

It is not a de Polignac number, because 20611961 - 2¹⁴ = 20595577 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 20611961.

It is not an unprimeable number, because it can be changed into a prime (20611967) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 168890 + ... + 169011.

It is an arithmetic number, because the mean of its divisors is an integer number (5237481).

Almost surely, 2^20611961 is an apocalyptic number.

It is an amenable number.

20611961 is a deficient number, since it is larger than the sum of its proper divisors (337963).

20611961 is an equidigital number, since it uses as much as digits as its factorization.

20611961 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 337962.

The product of its (nonzero) digits is 648, while the sum is 26.

The square root of 20611961 is about 4540.0397575352. The cubic root of 20611961 is about 274.1825244146.

It can be divided in two parts, 206 and 11961, that added together give a cube (12167 = 23³).

The spelling of 20611961 in words is "twenty million, six hundred eleven thousand, nine hundred sixty-one".