20397581251 has 2 divisors, whose sum is σ = 20397581252. Its totient is φ = 20397581250.

The previous prime is 20397581231. The next prime is 20397581273. The reversal of 20397581251 is 15218579302.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20397581251 - 2⁷ = 20397581123 is a prime.

It is a super-2 number, since 2×20397581251² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20397581198 and 20397581207.

It is not a weakly prime, because it can be changed into another prime (20397581231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10198790625 + 10198790626.

It is an arithmetic number, because the mean of its divisors is an integer number (10198790626).

Almost surely, 2^20397581251 is an apocalyptic number.

20397581251 is a deficient number, since it is larger than the sum of its proper divisors (1).

20397581251 is an equidigital number, since it uses as much as digits as its factorization.

20397581251 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 151200, while the sum is 43.

The spelling of 20397581251 in words is "twenty billion, three hundred ninety-seven million, five hundred eighty-one thousand, two hundred fifty-one".