21786942 has 16 divisors (see below), whose sum is σ = 43666560. Its totient is φ = 7246872.

The previous prime is 21786937. The next prime is 21786953. The reversal of 21786942 is 24968712.

It is a super-2 number, since 2×21786942² = 949341683422728, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21786942.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 592 + ... + 6627.

It is an arithmetic number, because the mean of its divisors is an integer number (2729160).

Almost surely, 2^21786942 is an apocalyptic number.

21786942 is an abundant number, since it is smaller than the sum of its proper divisors (21879618).

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

21786942 is a wasteful number, since it uses less digits than its factorization.

21786942 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7727.

The product of its digits is 48384, while the sum is 39.

The square root of 21786942 is about 4667.6484443454. The cubic root of 21786942 is about 279.2964565074.

The spelling of 21786942 in words is "twenty-one million, seven hundred eighty-six thousand, nine hundred forty-two".