21317650 has 12 divisors (see below), whose sum is σ = 39650922. Its totient is φ = 8527040.

The previous prime is 21317627. The next prime is 21317651. The reversal of 21317650 is 5671312.

It can be written as a sum of positive squares in 3 ways, for example, as 19722481 + 1595169 = 4441^2 + 1263^2 .

It is a Harshad number since it is a multiple of its sum of digits (25).

It is not an unprimeable number, because it can be changed into a prime (21317651) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 213127 + ... + 213226.

Almost surely, 2^21317650 is an apocalyptic number.

21317650 is a deficient number, since it is larger than the sum of its proper divisors (18333272).

21317650 is a wasteful number, since it uses less digits than its factorization.

21317650 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 426365 (or 426360 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 25.

The square root of 21317650 is about 4617.1040707352. The cubic root of 21317650 is about 277.2765292289.

Adding to 21317650 its reverse (5671312), we get a palindrome (26988962).

The spelling of 21317650 in words is "twenty-one million, three hundred seventeen thousand, six hundred fifty".