20521811 has 2 divisors, whose sum is σ = 20521812. Its totient is φ = 20521810.

The previous prime is 20521807. The next prime is 20521829. The reversal of 20521811 is 11812502.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20521811 - 2² = 20521807 is a prime.

It is a super-2 number, since 2×20521811² = 842289453439442, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20521841) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10260905 + 10260906.

It is an arithmetic number, because the mean of its divisors is an integer number (10260906).

Almost surely, 2^20521811 is an apocalyptic number.

20521811 is a deficient number, since it is larger than the sum of its proper divisors (1).

20521811 is an equidigital number, since it uses as much as digits as its factorization.

20521811 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 160, while the sum is 20.

The square root of 20521811 is about 4530.1005507604. The cubic root of 20521811 is about 273.7822118986.

The spelling of 20521811 in words is "twenty million, five hundred twenty-one thousand, eight hundred eleven".