1551621072557 has 4 divisors (see below), whose sum is σ = 1574779596096. Its totient is φ = 1528462549020.

The previous prime is 1551621072493. The next prime is 1551621072559. The reversal of 1551621072557 is 7552701261551.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1551621072557 - 2⁶ = 1551621072493 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1551621072559) 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, 11579261669 + ... + 11579261802.

It is an arithmetic number, because the mean of its divisors is an integer number (393694899024).

Almost surely, 2^{1551621072557} is an apocalyptic number.

It is an amenable number.

1551621072557 is a deficient number, since it is larger than the sum of its proper divisors (23158523539).

1551621072557 is an equidigital number, since it uses as much as digits as its factorization.

1551621072557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23158523538.

The product of its (nonzero) digits is 735000, while the sum is 47.

The spelling of 1551621072557 in words is "one trillion, five hundred fifty-one billion, six hundred twenty-one million, seventy-two thousand, five hundred fifty-seven".