20987801 has 2 divisors, whose sum is σ = 20987802. Its totient is φ = 20987800.

The previous prime is 20987797. The next prime is 20987807. The reversal of 20987801 is 10878902.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11526025 + 9461776 = 3395^2 + 3076^2 .

It is a cyclic number.

It is not a de Polignac number, because 20987801 - 2² = 20987797 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20987807) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10493900 + 10493901.

It is an arithmetic number, because the mean of its divisors is an integer number (10493901).

Almost surely, 2^20987801 is an apocalyptic number.

It is an amenable number.

20987801 is a deficient number, since it is larger than the sum of its proper divisors (1).

20987801 is an equidigital number, since it uses as much as digits as its factorization.

20987801 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8064, while the sum is 35.

The square root of 20987801 is about 4581.2444815792. The cubic root of 20987801 is about 275.8389848839.

The spelling of 20987801 in words is "twenty million, nine hundred eighty-seven thousand, eight hundred one".