1251633540 has 24 divisors (see below), whose sum is σ = 3504574080. Its totient is φ = 333768928.

The previous prime is 1251633529. The next prime is 1251633541. The reversal of 1251633540 is 453361521.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 1251633498 and 1251633507.

It is not an unprimeable number, because it can be changed into a prime (1251633541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10430220 + ... + 10430339.

It is an arithmetic number, because the mean of its divisors is an integer number (146023920).

Almost surely, 2^1251633540 is an apocalyptic number.

1251633540 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1251633540 is an abundant number, since it is smaller than the sum of its proper divisors (2252940540).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1251633540 is a wasteful number, since it uses less digits than its factorization.

1251633540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20860571 (or 20860569 counting only the distinct ones).

The product of its (nonzero) digits is 10800, while the sum is 30.

The square root of 1251633540 is about 35378.4332609572. The cubic root of 1251633540 is about 1077.6863881209.

It can be divided in two parts, 12516 and 33540, that added together give a triangular number (46056 = T₃₀₃).

The spelling of 1251633540 in words is "one billion, two hundred fifty-one million, six hundred thirty-three thousand, five hundred forty".