21163870 has 48 divisors (see below), whose sum is σ = 47170080. Its totient is φ = 6694272.

The previous prime is 21163867. The next prime is 21163927. The reversal of 21163870 is 7836112.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10936 + ... + 12724.

It is an arithmetic number, because the mean of its divisors is an integer number (982710).

Almost surely, 2^21163870 is an apocalyptic number.

21163870 is an abundant number, since it is smaller than the sum of its proper divisors (26006210).

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

21163870 is a wasteful number, since it uses less digits than its factorization.

21163870 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1829 (or 1816 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 28.

The square root of 21163870 is about 4600.4206329422. The cubic root of 21163870 is about 276.6081858943.

Adding to 21163870 its reverse (7836112), we get a palindrome (28999982).

The spelling of 21163870 in words is "twenty-one million, one hundred sixty-three thousand, eight hundred seventy".