21948731 has 16 divisors (see below), whose sum is σ = 25968384. Its totient is φ = 18162144.

The previous prime is 21948721. The next prime is 21948749. The reversal of 21948731 is 13784912.

It is not a de Polignac number, because 21948731 - 2¹⁰ = 21947707 is a prime.

It is a super-2 number, since 2×21948731² = 963493585020722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21948691 and 21948700.

It is not an unprimeable number, because it can be changed into a prime (21948721) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24416 + ... + 25298.

It is an arithmetic number, because the mean of its divisors is an integer number (1623024).

Almost surely, 2^21948731 is an apocalyptic number.

21948731 is a deficient number, since it is larger than the sum of its proper divisors (4019653).

21948731 is an equidigital number, since it uses as much as digits as its factorization.

21948731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1010.

The product of its digits is 12096, while the sum is 35.

The square root of 21948731 is about 4684.9472782519. The cubic root of 21948731 is about 279.9861005005.

The spelling of 21948731 in words is "twenty-one million, nine hundred forty-eight thousand, seven hundred thirty-one".