21423770 has 8 divisors (see below), whose sum is σ = 38562804. Its totient is φ = 8569504.

The previous prime is 21423769. The next prime is 21423781. The reversal of 21423770 is 7732412.

It can be written as a sum of positive squares in 2 ways, for example, as 21409129 + 14641 = 4627^2 + 121^2 .

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, 1071179 + ... + 1071198.

Almost surely, 2^21423770 is an apocalyptic number.

21423770 is a deficient number, since it is larger than the sum of its proper divisors (17139034).

21423770 is a wasteful number, since it uses less digits than its factorization.

21423770 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2142384.

The product of its (nonzero) digits is 2352, while the sum is 26.

The square root of 21423770 is about 4628.5818562493. The cubic root of 21423770 is about 277.7358652615.

The spelling of 21423770 in words is "twenty-one million, four hundred twenty-three thousand, seven hundred seventy".