20701210781 has 2 divisors, whose sum is σ = 20701210782. Its totient is φ = 20701210780.

The previous prime is 20701210763. The next prime is 20701210807. The reversal of 20701210781 is 18701210702.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14875705156 + 5825505625 = 121966^2 + 76325^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20701210781 is a prime.

It is a super-2 number, since 2×20701210781² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20701210381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10350605390 + 10350605391.

It is an arithmetic number, because the mean of its divisors is an integer number (10350605391).

Almost surely, 2^20701210781 is an apocalyptic number.

It is an amenable number.

20701210781 is a deficient number, since it is larger than the sum of its proper divisors (1).

20701210781 is an equidigital number, since it uses as much as digits as its factorization.

20701210781 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1568, while the sum is 29.

The spelling of 20701210781 in words is "twenty billion, seven hundred one million, two hundred ten thousand, seven hundred eighty-one".