21630736 has 10 divisors (see below), whose sum is σ = 41909582. Its totient is φ = 10815360.

The previous prime is 21630733. The next prime is 21630761. The reversal of 21630736 is 63703612.

It can be written as a sum of positive squares in only one way, i.e., 13542400 + 8088336 = 3680^2 + 2844^2 .

It is a super-3 number, since 3×21630736³ (a number of 23 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (21630733) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 675945 + ... + 675976.

Almost surely, 2^21630736 is an apocalyptic number.

It is an amenable number.

21630736 is a deficient number, since it is larger than the sum of its proper divisors (20278846).

21630736 is a wasteful number, since it uses less digits than its factorization.

21630736 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1351929 (or 1351923 counting only the distinct ones).

The product of its (nonzero) digits is 4536, while the sum is 28.

The square root of 21630736 is about 4650.8855070836. The cubic root of 21630736 is about 278.6273635903.

It can be divided in two parts, 21630 and 736, that added together give a triangular number (22366 = T₂₁₁).

The spelling of 21630736 in words is "twenty-one million, six hundred thirty thousand, seven hundred thirty-six".