1551440251 has 4 divisors (see below), whose sum is σ = 1551533872. Its totient is φ = 1551346632.

The previous prime is 1551440239. The next prime is 1551440263. The reversal of 1551440251 is 1520441551.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1520441551 = 29 ⋅52429019.

It is an interprime number because it is at equal distance from previous prime (1551440239) and next prime (1551440263).

It is a cyclic number.

It is not a de Polignac number, because 1551440251 - 2¹⁵ = 1551407483 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1551440201) 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, 14535 + ... + 57568.

It is an arithmetic number, because the mean of its divisors is an integer number (387883468).

Almost surely, 2^1551440251 is an apocalyptic number.

1551440251 is a deficient number, since it is larger than the sum of its proper divisors (93621).

1551440251 is an equidigital number, since it uses as much as digits as its factorization.

1551440251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 93620.

The product of its (nonzero) digits is 4000, while the sum is 28.

The square root of 1551440251 is about 39388.3263290026. The cubic root of 1551440251 is about 1157.6528667485.

The spelling of 1551440251 in words is "one billion, five hundred fifty-one million, four hundred forty thousand, two hundred fifty-one".