20725151521 has 2 divisors, whose sum is σ = 20725151522. Its totient is φ = 20725151520.

The previous prime is 20725151507. The next prime is 20725151539. The reversal of 20725151521 is 12515152702.

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., 17930549025 + 2794602496 = 133905^2 + 52864^2 .

It is a cyclic number.

It is not a de Polignac number, because 20725151521 - 2⁷ = 20725151393 is a prime.

It is a super-2 number, since 2×20725151521² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20725151501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10362575760 + 10362575761.

It is an arithmetic number, because the mean of its divisors is an integer number (10362575761).

Almost surely, 2^20725151521 is an apocalyptic number.

It is an amenable number.

20725151521 is a deficient number, since it is larger than the sum of its proper divisors (1).

20725151521 is an equidigital number, since it uses as much as digits as its factorization.

20725151521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7000, while the sum is 31.

The spelling of 20725151521 in words is "twenty billion, seven hundred twenty-five million, one hundred fifty-one thousand, five hundred twenty-one".