1257621223681 has 4 divisors (see below), whose sum is σ = 1259659508292. Its totient is φ = 1255582939072.

The previous prime is 1257621223633. The next prime is 1257621223687. The reversal of 1257621223681 is 1863221267521.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 31076048656 + 1226545175025 = 176284^2 + 1107495^2 .

It is a cyclic number.

It is not a de Polignac number, because 1257621223681 - 2²¹ = 1257619126529 is a prime.

It is a super-2 number, since 2×1257621223681² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1257621223687) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1019141380 + ... + 1019142613.

It is an arithmetic number, because the mean of its divisors is an integer number (314914877073).

Almost surely, 2^{1257621223681} is an apocalyptic number.

It is an amenable number.

1257621223681 is a deficient number, since it is larger than the sum of its proper divisors (2038284611).

1257621223681 is an equidigital number, since it uses as much as digits as its factorization.

1257621223681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2038284610.

The product of its digits is 483840, while the sum is 46.

The spelling of 1257621223681 in words is "one trillion, two hundred fifty-seven billion, six hundred twenty-one million, two hundred twenty-three thousand, six hundred eighty-one".