21886861 has 6 divisors (see below), whose sum is σ = 22282862. Its totient is φ = 21492120.

The previous prime is 21886859. The next prime is 21886877. The reversal of 21886861 is 16868812.

It can be written as a sum of positive squares in only one way, i.e., 12916836 + 8970025 = 3594^2 + 2995^2 .

It is not a de Polignac number, because 21886861 - 2¹ = 21886859 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 (21886831) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 36240 + ... + 36838.

Almost surely, 2^21886861 is an apocalyptic number.

It is an amenable number.

21886861 is a deficient number, since it is larger than the sum of its proper divisors (396001).

21886861 is an frugal number, since it uses more digits than its factorization.

21886861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1259 (or 660 counting only the distinct ones).

The product of its digits is 36864, while the sum is 40.

The square root of 21886861 is about 4678.3395558681. The cubic root of 21886861 is about 279.7227740807.

The spelling of 21886861 in words is "twenty-one million, eight hundred eighty-six thousand, eight hundred sixty-one".