21206770 has 16 divisors (see below), whose sum is σ = 41108760. Its totient is φ = 7830144.

The previous prime is 21206753. The next prime is 21206791. The reversal of 21206770 is 7760212.

It can be written as a sum of positive squares in 4 ways, for example, as 10323369 + 10883401 = 3213^2 + 3299^2 .

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, 81435 + ... + 81694.

Almost surely, 2^21206770 is an apocalyptic number.

21206770 is a deficient number, since it is larger than the sum of its proper divisors (19901990).

21206770 is a wasteful number, since it uses less digits than its factorization.

21206770 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 163149.

The product of its (nonzero) digits is 1176, while the sum is 25.

The square root of 21206770 is about 4605.0808896262. The cubic root of 21206770 is about 276.7949583236.

Adding to 21206770 its reverse (7760212), we get a palindrome (28966982).

The spelling of 21206770 in words is "twenty-one million, two hundred six thousand, seven hundred seventy".