21713810 has 16 divisors (see below), whose sum is σ = 39187800. Its totient is φ = 8662656.

The previous prime is 21713807. The next prime is 21713819. The reversal of 21713810 is 1831712.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 15124321 + 6589489 = 3889^2 + 2567^2 .

It is a super-2 number, since 2×21713810² = 942979089432200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21713819) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1436 + ... + 6744.

Almost surely, 2^21713810 is an apocalyptic number.

21713810 is a deficient number, since it is larger than the sum of its proper divisors (17473990).

21713810 is a wasteful number, since it uses less digits than its factorization.

21713810 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5725.

The product of its (nonzero) digits is 336, while the sum is 23.

The square root of 21713810 is about 4659.8079359562. The cubic root of 21713810 is about 278.9836023644.

The spelling of 21713810 in words is "twenty-one million, seven hundred thirteen thousand, eight hundred ten".