21820970 has 8 divisors (see below), whose sum is σ = 39277764. Its totient is φ = 8728384.

The previous prime is 21820957. The next prime is 21820991. The reversal of 21820970 is 7902812.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 21335161 + 485809 = 4619^2 + 697^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

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 3 ways as a sum of consecutive naturals, for example, 1091039 + ... + 1091058.

Almost surely, 2^21820970 is an apocalyptic number.

21820970 is a deficient number, since it is larger than the sum of its proper divisors (17456794).

21820970 is a wasteful number, since it uses less digits than its factorization.

21820970 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2182104.

The product of its (nonzero) digits is 2016, while the sum is 29.

The square root of 21820970 is about 4671.2921124674. The cubic root of 21820970 is about 279.4417875381.

The spelling of 21820970 in words is "twenty-one million, eight hundred twenty thousand, nine hundred seventy".