21397705 has 32 divisors (see below), whose sum is σ = 32256000. Its totient is φ = 13286592.

The previous prime is 21397699. The next prime is 21397711. The reversal of 21397705 is 50779312.

It is an interprime number because it is at equal distance from previous prime (21397699) and next prime (21397711).

It is a cyclic number.

It is not a de Polignac number, because 21397705 - 2³ = 21397697 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 14596 + ... + 15994.

It is an arithmetic number, because the mean of its divisors is an integer number (1008000).

Almost surely, 2^21397705 is an apocalyptic number.

It is an amenable number.

21397705 is a deficient number, since it is larger than the sum of its proper divisors (10858295).

21397705 is a wasteful number, since it uses less digits than its factorization.

21397705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1453.

The product of its (nonzero) digits is 13230, while the sum is 34.

The square root of 21397705 is about 4625.7653420812. The cubic root of 21397705 is about 277.6231847647.

The spelling of 21397705 in words is "twenty-one million, three hundred ninety-seven thousand, seven hundred five".