21777970 has 16 divisors (see below), whose sum is σ = 40157208. Its totient is φ = 8498560.

The previous prime is 21777953. The next prime is 21777979. The reversal of 21777970 is 7977712.

It can be written as a sum of positive squares in 4 ways, for example, as 17380561 + 4397409 = 4169^2 + 2097^2 .

It is not an unprimeable number, because it can be changed into a prime (21777979) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26149 + ... + 26968.

Almost surely, 2^21777970 is an apocalyptic number.

21777970 is a deficient number, since it is larger than the sum of its proper divisors (18379238).

21777970 is a wasteful number, since it uses less digits than its factorization.

21777970 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53165.

The product of its (nonzero) digits is 43218, while the sum is 40.

The square root of 21777970 is about 4666.6872618593. The cubic root of 21777970 is about 279.2581125633.

It can be divided in two parts, 217 and 77970, that added together give a palindrome (78187).

The spelling of 21777970 in words is "twenty-one million, seven hundred seventy-seven thousand, nine hundred seventy".