21945742 has 64 divisors (see below), whose sum is σ = 44198784. Its totient is φ = 7925760.

The previous prime is 21945689. The next prime is 21945751. The reversal of 21945742 is 24754912.

It is a Harshad number since it is a multiple of its sum of digits (34).

It is a junction number, because it is equal to n+sod(n) for n = 21945698 and 21945707.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 126768 + ... + 126940.

It is an arithmetic number, because the mean of its divisors is an integer number (690606).

Almost surely, 2^21945742 is an apocalyptic number.

21945742 is an abundant number, since it is smaller than the sum of its proper divisors (22253042).

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

21945742 is a wasteful number, since it uses less digits than its factorization.

21945742 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 253.

The product of its digits is 20160, while the sum is 34.

The square root of 21945742 is about 4684.6282670026. The cubic root of 21945742 is about 279.9733903284.

The spelling of 21945742 in words is "twenty-one million, nine hundred forty-five thousand, seven hundred forty-two".