21895949 has 4 divisors (see below), whose sum is σ = 23183964.
Its totient is φ = 20607936.
The previous prime is 21895933. The next prime is 21895969. The reversal of 21895949 is 94959812.
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 19624900 + 2271049 = 4430^2 + 1507^2
It is a cyclic number.
It is not a de Polignac number, because 21895949 - 24 = 21895933 is a prime.
It is a super-3 number, since 3×218959493 (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.
It is a Duffinian number.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (21895969) 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, 643982 + ... + 644015.
It is an arithmetic number, because the mean of its divisors is an integer number (5795991).
Almost surely, 221895949 is an apocalyptic number.
It is an amenable number.
21895949 is a deficient number, since it is larger than the sum of its proper divisors (1288015).
21895949 is a wasteful number, since it uses less digits than its factorization.
21895949 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 1288014.
The product of its digits is 233280, while the sum is 47.
The square root of 21895949 is about 4679.3107398419.
The cubic root of 21895949 is about 279.7614848061.
The spelling of 21895949 in words is "twenty-one million, eight hundred ninety-five thousand, nine hundred forty-nine".