21742745 has 16 divisors (see below), whose sum is σ = 29082240. Its totient is φ = 15508224.

The previous prime is 21742727. The next prime is 21742753. The reversal of 21742745 is 54724712.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21742745 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5117 + ... + 8346.

It is an arithmetic number, because the mean of its divisors is an integer number (1817640).

Almost surely, 2^21742745 is an apocalyptic number.

It is an amenable number.

21742745 is a deficient number, since it is larger than the sum of its proper divisors (7339495).

21742745 is a wasteful number, since it uses less digits than its factorization.

21742745 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13504.

The product of its digits is 15680, while the sum is 32.

The square root of 21742745 is about 4662.9116440267. The cubic root of 21742745 is about 279.1074683516.

The spelling of 21742745 in words is "twenty-one million, seven hundred forty-two thousand, seven hundred forty-five".