21870116 has 6 divisors (see below), whose sum is σ = 38272710. Its totient is φ = 10935056.

The previous prime is 21870103. The next prime is 21870127. The reversal of 21870116 is 61107812.

It can be written as a sum of positive squares in only one way, i.e., 18028516 + 3841600 = 4246^2 + 1960^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2733761 + ... + 2733768.

It is an arithmetic number, because the mean of its divisors is an integer number (6378785).

Almost surely, 2^21870116 is an apocalyptic number.

It is an amenable number.

21870116 is a deficient number, since it is larger than the sum of its proper divisors (16402594).

21870116 is a wasteful number, since it uses less digits than its factorization.

21870116 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5467533 (or 5467531 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 26.

The square root of 21870116 is about 4676.5495827586. The cubic root of 21870116 is about 279.6514199643.

Adding to 21870116 its reverse (61107812), we get a palindrome (82977928).

Subtracting 21870116 from its reverse (61107812), we obtain a square (39237696 = 6264²).

The spelling of 21870116 in words is "twenty-one million, eight hundred seventy thousand, one hundred sixteen".