21165970 has 32 divisors (see below), whose sum is σ = 44201088. Its totient is φ = 7147008.

The previous prime is 21165967. The next prime is 21165971. The reversal of 21165970 is 7956112.

It is not an unprimeable number, because it can be changed into a prime (21165971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2434 + ... + 6946.

It is an arithmetic number, because the mean of its divisors is an integer number (1381284).

Almost surely, 2^21165970 is an apocalyptic number.

21165970 is an abundant number, since it is smaller than the sum of its proper divisors (23035118).

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

21165970 is a wasteful number, since it uses less digits than its factorization.

21165970 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4594.

The product of its (nonzero) digits is 3780, while the sum is 31.

The square root of 21165970 is about 4600.6488672795. The cubic root of 21165970 is about 276.6173344728.

The spelling of 21165970 in words is "twenty-one million, one hundred sixty-five thousand, nine hundred seventy".