21742641 has 16 divisors (see below), whose sum is σ = 32430720. Its totient is φ = 14396400.

The previous prime is 21742627. The next prime is 21742691. The reversal of 21742641 is 14624712.

21742641 is a `hidden beast` number, since 2 + 17 + 4 + 2 + 641 = 666.

It is not a de Polignac number, because 21742641 - 2⁶ = 21742577 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21742691) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 1411 + ... + 6743.

It is an arithmetic number, because the mean of its divisors is an integer number (2026920).

Almost surely, 2^21742641 is an apocalyptic number.

It is an amenable number.

21742641 is a deficient number, since it is larger than the sum of its proper divisors (10688079).

21742641 is a wasteful number, since it uses less digits than its factorization.

21742641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5493 (or 5487 counting only the distinct ones).

The product of its digits is 2688, while the sum is 27.

The square root of 21742641 is about 4662.9004921830. The cubic root of 21742641 is about 279.1070233415.

The spelling of 21742641 in words is "twenty-one million, seven hundred forty-two thousand, six hundred forty-one".