21779742 has 16 divisors (see below), whose sum is σ = 43754112. Its totient is φ = 7227480.

The previous prime is 21779731. The next prime is 21779759. The reversal of 21779742 is 24797712.

It is a self number, because there is not a number n which added to its sum of digits gives 21779742.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6634 + ... + 9357.

It is an arithmetic number, because the mean of its divisors is an integer number (2734632).

Almost surely, 2^21779742 is an apocalyptic number.

21779742 is an abundant number, since it is smaller than the sum of its proper divisors (21974370).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21779742 is a wasteful number, since it uses less digits than its factorization.

21779742 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16223.

The product of its digits is 49392, while the sum is 39.

The square root of 21779742 is about 4666.8771143025. The cubic root of 21779742 is about 279.2656864549.

The spelling of 21779742 in words is "twenty-one million, seven hundred seventy-nine thousand, seven hundred forty-two".