21939785 has 32 divisors (see below), whose sum is σ = 31598592. Its totient is φ = 14307840.

The previous prime is 21939767. The next prime is 21939791. The reversal of 21939785 is 58793912.

It is not a de Polignac number, because 21939785 - 2⁸ = 21939529 is a prime.

It is a Duffinian number.

It is a Curzon number.

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, 79067 + ... + 79343.

It is an arithmetic number, because the mean of its divisors is an integer number (987456).

Almost surely, 2^21939785 is an apocalyptic number.

It is an amenable number.

21939785 is a deficient number, since it is larger than the sum of its proper divisors (9658807).

21939785 is a wasteful number, since it uses less digits than its factorization.

21939785 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 393.

The product of its digits is 136080, while the sum is 44.

The square root of 21939785 is about 4683.9924210016. The cubic root of 21939785 is about 279.9480558404.

It can be divided in two parts, 219 and 39785, that added together give a palindrome (40004).

The spelling of 21939785 in words is "twenty-one million, nine hundred thirty-nine thousand, seven hundred eighty-five".