20630756921 has 2 divisors, whose sum is σ = 20630756922. Its totient is φ = 20630756920.

The previous prime is 20630756917. The next prime is 20630756941. The reversal of 20630756921 is 12965703602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10351027600 + 10279729321 = 101740^2 + 101389^2 .

It is a cyclic number.

It is not a de Polignac number, because 20630756921 - 2² = 20630756917 is a prime.

It is a super-2 number, since 2×20630756921² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20630756941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10315378460 + 10315378461.

It is an arithmetic number, because the mean of its divisors is an integer number (10315378461).

Almost surely, 2^20630756921 is an apocalyptic number.

It is an amenable number.

20630756921 is a deficient number, since it is larger than the sum of its proper divisors (1).

20630756921 is an equidigital number, since it uses as much as digits as its factorization.

20630756921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 136080, while the sum is 41.

The spelling of 20630756921 in words is "twenty billion, six hundred thirty million, seven hundred fifty-six thousand, nine hundred twenty-one".