21997070 has 16 divisors (see below), whose sum is σ = 39745728. Its totient is φ = 8765280.

The previous prime is 21997069. The next prime is 21997091. The reversal of 21997070 is 7079912.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21997070.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 1349 + ... + 6768.

It is an arithmetic number, because the mean of its divisors is an integer number (2484108).

Almost surely, 2^21997070 is an apocalyptic number.

21997070 is a deficient number, since it is larger than the sum of its proper divisors (17748658).

21997070 is a wasteful number, since it uses less digits than its factorization.

21997070 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8395.

The product of its (nonzero) digits is 7938, while the sum is 35.

The square root of 21997070 is about 4690.1034103738. The cubic root of 21997070 is about 280.1914931568.

The spelling of 21997070 in words is "twenty-one million, nine hundred ninety-seven thousand, seventy".