21858949 has 24 divisors (see below), whose sum is σ = 27332640. Its totient is φ = 17375904.

The previous prime is 21858931. The next prime is 21858979. The reversal of 21858949 is 94985812.

It is a de Polignac number, because none of the positive numbers 2^k-21858949 is a prime.

It is a super-3 number, since 3×21858949³ (a number of 23 digits) contains 333 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a junction number, because it is equal to n+sod(n) for n = 21858899 and 21858908.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21858929) 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 23 ways as a sum of consecutive naturals, for example, 49122 + ... + 49564.

It is an arithmetic number, because the mean of its divisors is an integer number (1138860).

Almost surely, 2^21858949 is an apocalyptic number.

It is an amenable number.

21858949 is a deficient number, since it is larger than the sum of its proper divisors (5473691).

21858949 is a wasteful number, since it uses less digits than its factorization.

21858949 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 529 (or 522 counting only the distinct ones).

The product of its digits is 207360, while the sum is 46.

The square root of 21858949 is about 4675.3554945052. The cubic root of 21858949 is about 279.6038146829.

The spelling of 21858949 in words is "twenty-one million, eight hundred fifty-eight thousand, nine hundred forty-nine".