21531707 has 8 divisors (see below), whose sum is σ = 22980096. Its totient is φ = 20103552.

The previous prime is 21531689. The next prime is 21531709. The reversal of 21531707 is 70713512.

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 21531707 - 2¹⁶ = 21466171 is a prime.

It is a super-2 number, since 2×21531707² = 927228812667698, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21531709) 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 7 ways as a sum of consecutive naturals, for example, 2828 + ... + 7145.

It is an arithmetic number, because the mean of its divisors is an integer number (2872512).

Almost surely, 2^21531707 is an apocalyptic number.

21531707 is a deficient number, since it is larger than the sum of its proper divisors (1448389).

21531707 is a wasteful number, since it uses less digits than its factorization.

21531707 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10117.

The product of its (nonzero) digits is 1470, while the sum is 26.

The square root of 21531707 is about 4640.2270418591. The cubic root of 21531707 is about 278.2015127119.

The spelling of 21531707 in words is "twenty-one million, five hundred thirty-one thousand, seven hundred seven".