21706929 has 6 divisors (see below), whose sum is σ = 31354466. Its totient is φ = 14471280.

The previous prime is 21706921. The next prime is 21706931. The reversal of 21706929 is 92960712.

It can be written as a sum of positive squares in only one way, i.e., 12616704 + 9090225 = 3552^2 + 3015^2 .

It is not a de Polignac number, because 21706929 - 2³ = 21706921 is a prime.

It is a super-2 number, since 2×21706929² = 942381533222082, 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 = 21706893 and 21706902.

It is not an unprimeable number, because it can be changed into a prime (21706921) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1205932 + ... + 1205949.

Almost surely, 2^21706929 is an apocalyptic number.

It is an amenable number.

21706929 is a deficient number, since it is larger than the sum of its proper divisors (9647537).

21706929 is a wasteful number, since it uses less digits than its factorization.

21706929 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2411887 (or 2411884 counting only the distinct ones).

The product of its (nonzero) digits is 13608, while the sum is 36.

The square root of 21706929 is about 4659.0695423013. The cubic root of 21706929 is about 278.9541297387.

The spelling of 21706929 in words is "twenty-one million, seven hundred six thousand, nine hundred twenty-nine".