1251449661557 has 8 divisors (see below), whose sum is σ = 1281987510720. Its totient is φ = 1220912511840.

The previous prime is 1251449661499. The next prime is 1251449661601. The reversal of 1251449661557 is 7551669441521.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1251449661557 - 2²² = 1251445467253 is a prime.

It is a super-2 number, since 2×1251449661557² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1251449669557) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6798944 + ... + 6980582.

It is an arithmetic number, because the mean of its divisors is an integer number (160248438840).

Almost surely, 2^{1251449661557} is an apocalyptic number.

It is an amenable number.

1251449661557 is a deficient number, since it is larger than the sum of its proper divisors (30537849163).

1251449661557 is a wasteful number, since it uses less digits than its factorization.

1251449661557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 349723.

The product of its digits is 9072000, while the sum is 56.

The spelling of 1251449661557 in words is "one trillion, two hundred fifty-one billion, four hundred forty-nine million, six hundred sixty-one thousand, five hundred fifty-seven".