21785642 has 8 divisors (see below), whose sum is σ = 32700000. Its totient is φ = 10885644.

The previous prime is 21785629. The next prime is 21785657. The reversal of 21785642 is 24658712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×21785642² = 949228394704328, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1859 + ... + 6857.

It is an arithmetic number, because the mean of its divisors is an integer number (4087500).

Almost surely, 2^21785642 is an apocalyptic number.

21785642 is a deficient number, since it is larger than the sum of its proper divisors (10914358).

21785642 is a wasteful number, since it uses less digits than its factorization.

21785642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7180.

The product of its digits is 26880, while the sum is 35.

The square root of 21785642 is about 4667.5091858506. The cubic root of 21785642 is about 279.2909013050.

The spelling of 21785642 in words is "twenty-one million, seven hundred eighty-five thousand, six hundred forty-two".