21670971 has 16 divisors (see below), whose sum is σ = 34965504. Its totient is φ = 11654784.

The previous prime is 21670967. The next prime is 21670973. The reversal of 21670971 is 17907612.

It is not a de Polignac number, because 21670971 - 2² = 21670967 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21670973) 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, 29995 + ... + 30708.

It is an arithmetic number, because the mean of its divisors is an integer number (2185344).

Almost surely, 2^21670971 is an apocalyptic number.

21670971 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21670971 is a deficient number, since it is larger than the sum of its proper divisors (13294533).

21670971 is a wasteful number, since it uses less digits than its factorization.

21670971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60730.

The product of its (nonzero) digits is 5292, while the sum is 33.

The square root of 21670971 is about 4655.2090178638. The cubic root of 21670971 is about 278.8000134141.

The spelling of 21670971 in words is "twenty-one million, six hundred seventy thousand, nine hundred seventy-one".