21497636 has 6 divisors (see below), whose sum is σ = 37620870. Its totient is φ = 10748816.

The previous prime is 21497627. The next prime is 21497657. The reversal of 21497636 is 63679412.

It can be written as a sum of positive squares in only one way, i.e., 19307236 + 2190400 = 4394^2 + 1480^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21497636.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2687201 + ... + 2687208.

It is an arithmetic number, because the mean of its divisors is an integer number (6270145).

Almost surely, 2^21497636 is an apocalyptic number.

It is an amenable number.

21497636 is a deficient number, since it is larger than the sum of its proper divisors (16123234).

21497636 is a wasteful number, since it uses less digits than its factorization.

21497636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5374413 (or 5374411 counting only the distinct ones).

The product of its digits is 54432, while the sum is 38.

The square root of 21497636 is about 4636.5543240644. The cubic root of 21497636 is about 278.0546965510.

The spelling of 21497636 in words is "twenty-one million, four hundred ninety-seven thousand, six hundred thirty-six".