21887869 has 4 divisors (see below), whose sum is σ = 21958560. Its totient is φ = 21817180.

The previous prime is 21887851. The next prime is 21887893. The reversal of 21887869 is 96878812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21887869 - 2⁷ = 21887741 is a prime.

It is a super-2 number, since 2×21887869² = 958157618722322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21887839) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 34879 + ... + 35500.

It is an arithmetic number, because the mean of its divisors is an integer number (5489640).

Almost surely, 2^21887869 is an apocalyptic number.

It is an amenable number.

21887869 is a deficient number, since it is larger than the sum of its proper divisors (70691).

21887869 is an equidigital number, since it uses as much as digits as its factorization.

21887869 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70690.

The product of its digits is 387072, while the sum is 49.

The square root of 21887869 is about 4678.4472851578. The cubic root of 21887869 is about 279.7270682281.

The spelling of 21887869 in words is "twenty-one million, eight hundred eighty-seven thousand, eight hundred sixty-nine".