21704720331 has 16 divisors (see below), whose sum is σ = 33967748864. Its totient is φ = 12067488864.

The previous prime is 21704720327. The next prime is 21704720381. The reversal of 21704720331 is 13302740712.

It is not a de Polignac number, because 21704720331 - 2² = 21704720327 is a prime.

It is a super-2 number, since 2×21704720331² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21704720311) 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, 13966225 + ... + 13967778.

It is an arithmetic number, because the mean of its divisors is an integer number (2122984304).

Almost surely, 2^21704720331 is an apocalyptic number.

21704720331 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21704720331 is a deficient number, since it is larger than the sum of its proper divisors (12263028533).

21704720331 is a wasteful number, since it uses less digits than its factorization.

21704720331 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27934050.

The product of its (nonzero) digits is 7056, while the sum is 30.

The spelling of 21704720331 in words is "twenty-one billion, seven hundred four million, seven hundred twenty thousand, three hundred thirty-one".