21345705 has 24 divisors (see below), whose sum is σ = 37132992. Its totient is φ = 11343264.

The previous prime is 21345703. The next prime is 21345713. The reversal of 21345705 is 50754312.

It is a happy number.

It is not a de Polignac number, because 21345705 - 2¹ = 21345703 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21345703) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 14932 + ... + 16298.

It is an arithmetic number, because the mean of its divisors is an integer number (1547208).

Almost surely, 2^21345705 is an apocalyptic number.

It is an amenable number.

21345705 is a deficient number, since it is larger than the sum of its proper divisors (15787287).

21345705 is a wasteful number, since it uses less digits than its factorization.

21345705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1725 (or 1722 counting only the distinct ones).

The product of its (nonzero) digits is 4200, while the sum is 27.

The square root of 21345705 is about 4620.1412316075. The cubic root of 21345705 is about 277.3981120959.

The spelling of 21345705 in words is "twenty-one million, three hundred forty-five thousand, seven hundred five".