21489916 has 24 divisors (see below), whose sum is σ = 43112160. Its totient is φ = 9181632.

The previous prime is 21489911. The next prime is 21489917. The reversal of 21489916 is 61998412.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21489911) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9906 + ... + 11878.

It is an arithmetic number, because the mean of its divisors is an integer number (1796340).

Almost surely, 2^21489916 is an apocalyptic number.

It is an amenable number.

21489916 is an abundant number, since it is smaller than the sum of its proper divisors (21622244).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21489916 is a wasteful number, since it uses less digits than its factorization.

21489916 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2373 (or 2371 counting only the distinct ones).

The product of its digits is 31104, while the sum is 40.

The square root of 21489916 is about 4635.7217345307. The cubic root of 21489916 is about 278.0214085613.

The spelling of 21489916 in words is "twenty-one million, four hundred eighty-nine thousand, nine hundred sixteen".