21061736 has 8 divisors (see below), whose sum is σ = 39490770. Its totient is φ = 10530864.

The previous prime is 21061717. The next prime is 21061739. The reversal of 21061736 is 63716012.

It can be written as a sum of positive squares in only one way, i.e., 16859236 + 4202500 = 4106^2 + 2050^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is not an unprimeable number, because it can be changed into a prime (21061739) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1316351 + ... + 1316366.

Almost surely, 2^21061736 is an apocalyptic number.

It is an amenable number.

21061736 is a deficient number, since it is larger than the sum of its proper divisors (18429034).

21061736 is a wasteful number, since it uses less digits than its factorization.

21061736 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2632723 (or 2632719 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 26.

The square root of 21061736 is about 4589.3067014528. The cubic root of 21061736 is about 276.1625101895.

Adding to 21061736 its reverse (63716012), we get a palindrome (84777748).

The spelling of 21061736 in words is "twenty-one million, sixty-one thousand, seven hundred thirty-six".