21891516 has 24 divisors (see below), whose sum is σ = 51174144. Its totient is φ = 7283760.

The previous prime is 21891511. The next prime is 21891539. The reversal of 21891516 is 61519812.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21891511) 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, 6861 + ... + 9531.

It is an arithmetic number, because the mean of its divisors is an integer number (2132256).

Almost surely, 2^21891516 is an apocalyptic number.

It is an amenable number.

21891516 is an abundant number, since it is smaller than the sum of its proper divisors (29282628).

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

21891516 is a wasteful number, since it uses less digits than its factorization.

21891516 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3361 (or 3359 counting only the distinct ones).

The product of its digits is 4320, while the sum is 33.

The square root of 21891516 is about 4678.8370349906. The cubic root of 21891516 is about 279.7426035910.

The spelling of 21891516 in words is "twenty-one million, eight hundred ninety-one thousand, five hundred sixteen".