661969893457 has 2 divisors, whose sum is σ = 661969893458. Its totient is φ = 661969893456.

The previous prime is 661969893413. The next prime is 661969893617. The reversal of 661969893457 is 754398969166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 361710827776 + 300259065681 = 601424^2 + 547959^2 .

It is a cyclic number.

It is not a de Polignac number, because 661969893457 - 2⁷ = 661969893329 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 661969893457.

It is not a weakly prime, because it can be changed into another prime (661969893257) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330984946728 + 330984946729.

It is an arithmetic number, because the mean of its divisors is an integer number (330984946729).

Almost surely, 2^661969893457 is an apocalyptic number.

It is an amenable number.

661969893457 is a deficient number, since it is larger than the sum of its proper divisors (1).

661969893457 is an equidigital number, since it uses as much as digits as its factorization.

661969893457 is an evil number, because the sum of its binary digits is even.

The product of its digits is 529079040, while the sum is 73.

The spelling of 661969893457 in words is "six hundred sixty-one billion, nine hundred sixty-nine million, eight hundred ninety-three thousand, four hundred fifty-seven".