21021793 has 16 divisors (see below), whose sum is σ = 23821056. Its totient is φ = 18406080.

The previous prime is 21021779. The next prime is 21021799. The reversal of 21021793 is 39712012.

It is a cyclic number.

It is not a de Polignac number, because 21021793 - 2¹⁷ = 20890721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21021799) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 49723 + ... + 50143.

It is an arithmetic number, because the mean of its divisors is an integer number (1488816).

Almost surely, 2^21021793 is an apocalyptic number.

21021793 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21021793 is a deficient number, since it is larger than the sum of its proper divisors (2799263).

21021793 is a wasteful number, since it uses less digits than its factorization.

21021793 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 624.

The product of its (nonzero) digits is 756, while the sum is 25.

The square root of 21021793 is about 4584.9528896162. The cubic root of 21021793 is about 275.9878215238.

The spelling of 21021793 in words is "twenty-one million, twenty-one thousand, seven hundred ninety-three".