21742646 has 4 divisors (see below), whose sum is σ = 32613972. Its totient is φ = 10871322.

The previous prime is 21742627. The next prime is 21742691. The reversal of 21742646 is 64624712.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5435660 + ... + 5435663.

It is an arithmetic number, because the mean of its divisors is an integer number (8153493).

Almost surely, 2^21742646 is an apocalyptic number.

21742646 is a deficient number, since it is larger than the sum of its proper divisors (10871326).

21742646 is a wasteful number, since it uses less digits than its factorization.

21742646 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10871325.

The product of its digits is 16128, while the sum is 32.

The square root of 21742646 is about 4662.9010283299. The cubic root of 21742646 is about 279.1070447363.

The spelling of 21742646 in words is "twenty-one million, seven hundred forty-two thousand, six hundred forty-six".