21067861 has 4 divisors (see below), whose sum is σ = 21083500. Its totient is φ = 21052224.

The previous prime is 21067853. The next prime is 21067867. The reversal of 21067861 is 16876012.

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 12916836 + 8151025 = 3594^2 + 2855^2 .

It is a cyclic number.

It is not a de Polignac number, because 21067861 - 2³ = 21067853 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21067867) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5586 + ... + 8563.

It is an arithmetic number, because the mean of its divisors is an integer number (5270875).

Almost surely, 2^21067861 is an apocalyptic number.

It is an amenable number.

21067861 is a deficient number, since it is larger than the sum of its proper divisors (15639).

21067861 is a wasteful number, since it uses less digits than its factorization.

21067861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15638.

The product of its (nonzero) digits is 4032, while the sum is 31.

The square root of 21067861 is about 4589.9739650678. The cubic root of 21067861 is about 276.1892780279.

The spelling of 21067861 in words is "twenty-one million, sixty-seven thousand, eight hundred sixty-one".