21020521051 has 2 divisors, whose sum is σ = 21020521052. Its totient is φ = 21020521050.

The previous prime is 21020521019. The next prime is 21020521057. The reversal of 21020521051 is 15012502012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21020521051 - 2⁵ = 21020521019 is a prime.

It is not a weakly prime, because it can be changed into another prime (21020521057) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510260525 + 10510260526.

It is an arithmetic number, because the mean of its divisors is an integer number (10510260526).

Almost surely, 2^21020521051 is an apocalyptic number.

21020521051 is a deficient number, since it is larger than the sum of its proper divisors (1).

21020521051 is an equidigital number, since it uses as much as digits as its factorization.

21020521051 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 200, while the sum is 19.

The spelling of 21020521051 in words is "twenty-one billion, twenty million, five hundred twenty-one thousand, fifty-one".