21469881 has 4 divisors (see below), whose sum is σ = 28626512. Its totient is φ = 14313252.

The previous prime is 21469853. The next prime is 21469897. The reversal of 21469881 is 18896412.

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 not a de Polignac number, because 21469881 - 2⁵ = 21469849 is a prime.

It is a super-2 number, since 2×21469881² = 921911580308322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21465881) 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, 3578311 + ... + 3578316.

It is an arithmetic number, because the mean of its divisors is an integer number (7156628).

Almost surely, 2^21469881 is an apocalyptic number.

It is an amenable number.

21469881 is a deficient number, since it is larger than the sum of its proper divisors (7156631).

21469881 is an equidigital number, since it uses as much as digits as its factorization.

21469881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7156630.

The product of its digits is 27648, while the sum is 39.

The square root of 21469881 is about 4633.5602942014. The cubic root of 21469881 is about 277.9349821209.

The spelling of 21469881 in words is "twenty-one million, four hundred sixty-nine thousand, eight hundred eighty-one".