20739661 has 2 divisors, whose sum is σ = 20739662. Its totient is φ = 20739660.

The previous prime is 20739619. The next prime is 20739671. The reversal of 20739661 is 16693702.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13616100 + 7123561 = 3690^2 + 2669^2 .

It is a cyclic number.

It is not a de Polignac number, because 20739661 - 2²¹ = 18642509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20739601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10369830 + 10369831.

It is an arithmetic number, because the mean of its divisors is an integer number (10369831).

Almost surely, 2^20739661 is an apocalyptic number.

It is an amenable number.

20739661 is a deficient number, since it is larger than the sum of its proper divisors (1).

20739661 is an equidigital number, since it uses as much as digits as its factorization.

20739661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 13608, while the sum is 34.

The square root of 20739661 is about 4554.0817954885. The cubic root of 20739661 is about 274.7475854668.

The spelling of 20739661 in words is "twenty million, seven hundred thirty-nine thousand, six hundred sixty-one".