21516460 has 24 divisors (see below), whose sum is σ = 51639840. Its totient is φ = 7377024.

The previous prime is 21516437. The next prime is 21516487. The reversal of 21516460 is 6461512.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 76705 + ... + 76984.

It is an arithmetic number, because the mean of its divisors is an integer number (2151660).

Almost surely, 2^21516460 is an apocalyptic number.

21516460 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21516460 is an abundant number, since it is smaller than the sum of its proper divisors (30123380).

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

21516460 is a wasteful number, since it uses less digits than its factorization.

21516460 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 153705 (or 153703 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 21516460 is about 4638.5838356119. The cubic root of 21516460 is about 278.1358306602.

Adding to 21516460 its reverse (6461512), we get a palindrome (27977972).

The spelling of 21516460 in words is "twenty-one million, five hundred sixteen thousand, four hundred sixty".