21630717 has 6 divisors (see below), whose sum is σ = 31244382. Its totient is φ = 14420472.

The previous prime is 21630689. The next prime is 21630727. The reversal of 21630717 is 71703612.

21630717 is a `hidden beast` number, since 21 + 630 + 7 + 1 + 7 = 666.

It can be written as a sum of positive squares in only one way, i.e., 20602521 + 1028196 = 4539^2 + 1014^2 .

It is not a de Polignac number, because 21630717 - 2⁸ = 21630461 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21630727) 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, 1201698 + ... + 1201715.

It is an arithmetic number, because the mean of its divisors is an integer number (5207397).

Almost surely, 2^21630717 is an apocalyptic number.

It is an amenable number.

21630717 is a deficient number, since it is larger than the sum of its proper divisors (9613665).

21630717 is a wasteful number, since it uses less digits than its factorization.

21630717 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2403419 (or 2403416 counting only the distinct ones).

The product of its (nonzero) digits is 1764, while the sum is 27.

The square root of 21630717 is about 4650.8834644613. The cubic root of 21630717 is about 278.6272820100.

The spelling of 21630717 in words is "twenty-one million, six hundred thirty thousand, seven hundred seventeen".