21845731 has 8 divisors (see below), whose sum is σ = 23877504. Its totient is φ = 19896960.

The previous prime is 21845723. The next prime is 21845737. The reversal of 21845731 is 13754812.

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

It is a cyclic number.

It is not a de Polignac number, because 21845731 - 2³ = 21845723 is a prime.

It is a super-2 number, since 2×21845731² = 954471925848722, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21845693 and 21845702.

It is not an unprimeable number, because it can be changed into a prime (21845737) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20200 + ... + 21253.

It is an arithmetic number, because the mean of its divisors is an integer number (2984688).

Almost surely, 2^21845731 is an apocalyptic number.

21845731 is a deficient number, since it is larger than the sum of its proper divisors (2031773).

21845731 is a wasteful number, since it uses less digits than its factorization.

21845731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41501.

The product of its digits is 6720, while the sum is 31.

The square root of 21845731 is about 4673.9416983955. The cubic root of 21845731 is about 279.5474449643.

The spelling of 21845731 in words is "twenty-one million, eight hundred forty-five thousand, seven hundred thirty-one".