20947861 has 16 divisors (see below), whose sum is σ = 24402240. Its totient is φ = 17781120.

The previous prime is 20947811. The next prime is 20947867. The reversal of 20947861 is 16874902.

It is a cyclic number.

It is not a de Polignac number, because 20947861 - 2¹⁹ = 20423573 is a prime.

It is a Duffinian number.

It is a plaindrome in base 13.

It is a self number, because there is not a number n which added to its sum of digits gives 20947861.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20947867) 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, 14571 + ... + 15943.

It is an arithmetic number, because the mean of its divisors is an integer number (1525140).

Almost surely, 2^20947861 is an apocalyptic number.

It is an amenable number.

20947861 is a deficient number, since it is larger than the sum of its proper divisors (3454379).

20947861 is a wasteful number, since it uses less digits than its factorization.

20947861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1476.

The product of its (nonzero) digits is 24192, while the sum is 37.

The square root of 20947861 is about 4576.8833282049. The cubic root of 20947861 is about 275.6638989702.

The spelling of 20947861 in words is "twenty million, nine hundred forty-seven thousand, eight hundred sixty-one".