21605374 has 24 divisors (see below), whose sum is σ = 38052288. Its totient is φ = 9172800.

The previous prime is 21605369. The next prime is 21605399. The reversal of 21605374 is 47350612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10099 + ... + 12049.

It is an arithmetic number, because the mean of its divisors is an integer number (1585512).

Almost surely, 2^21605374 is an apocalyptic number.

21605374 is a deficient number, since it is larger than the sum of its proper divisors (16446914).

21605374 is a wasteful number, since it uses less digits than its factorization.

21605374 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2080 (or 2073 counting only the distinct ones).

The product of its (nonzero) digits is 5040, while the sum is 28.

The square root of 21605374 is about 4648.1581298402. The cubic root of 21605374 is about 278.5184243038.

Adding to 21605374 its reverse (47350612), we get a palindrome (68955986).

The spelling of 21605374 in words is "twenty-one million, six hundred five thousand, three hundred seventy-four".