21380516 has 12 divisors (see below), whose sum is σ = 38328780. Its totient is φ = 10429440.

The previous prime is 21380473. The next prime is 21380519. The reversal of 21380516 is 61508312.

It can be written as a sum of positive squares in 2 ways, for example, as 2856100 + 18524416 = 1690^2 + 4304^2 .

It is not an unprimeable number, because it can be changed into a prime (21380519) 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, 65021 + ... + 65348.

It is an arithmetic number, because the mean of its divisors is an integer number (3194065).

Almost surely, 2^21380516 is an apocalyptic number.

It is an amenable number.

21380516 is a deficient number, since it is larger than the sum of its proper divisors (16948264).

21380516 is a wasteful number, since it uses less digits than its factorization.

21380516 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 130414 (or 130412 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 26.

The square root of 21380516 is about 4623.9070059853. The cubic root of 21380516 is about 277.5488256484.

Adding to 21380516 its reverse (61508312), we get a palindrome (82888828).

The spelling of 21380516 in words is "twenty-one million, three hundred eighty thousand, five hundred sixteen".