21074681 has 2 divisors, whose sum is σ = 21074682. Its totient is φ = 21074680.

The previous prime is 21074657. The next prime is 21074689. The reversal of 21074681 is 18647012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12313081 + 8761600 = 3509^2 + 2960^2 .

It is a cyclic number.

It is not a de Polignac number, because 21074681 - 2²² = 16880377 is a prime.

It is a super-2 number, since 2×21074681² = 888284358503522, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21074689) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10537340 + 10537341.

It is an arithmetic number, because the mean of its divisors is an integer number (10537341).

Almost surely, 2^21074681 is an apocalyptic number.

It is an amenable number.

21074681 is a deficient number, since it is larger than the sum of its proper divisors (1).

21074681 is an equidigital number, since it uses as much as digits as its factorization.

21074681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2688, while the sum is 29.

The square root of 21074681 is about 4590.7168285574. The cubic root of 21074681 is about 276.2190770926.

The spelling of 21074681 in words is "twenty-one million, seventy-four thousand, six hundred eighty-one".