21958706 has 16 divisors (see below), whose sum is σ = 41065920. Its totient is φ = 8555280.

The previous prime is 21958693. The next prime is 21958709. The reversal of 21958706 is 60785912.

It is a self number, because there is not a number n which added to its sum of digits gives 21958706.

It is not an unprimeable number, because it can be changed into a prime (21958709) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 71141 + ... + 71448.

It is an arithmetic number, because the mean of its divisors is an integer number (2566620).

Almost surely, 2^21958706 is an apocalyptic number.

21958706 is a deficient number, since it is larger than the sum of its proper divisors (19107214).

21958706 is a wasteful number, since it uses less digits than its factorization.

21958706 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 142609.

The product of its (nonzero) digits is 30240, while the sum is 38.

The square root of 21958706 is about 4686.0117370745. The cubic root of 21958706 is about 280.0285090019.

It can be divided in two parts, 2195 and 8706, that added together give a palindrome (10901).

The spelling of 21958706 in words is "twenty-one million, nine hundred fifty-eight thousand, seven hundred six".