1249287921 has 16 divisors (see below), whose sum is σ = 2115196800. Its totient is φ = 713878704.

The previous prime is 1249287899. The next prime is 1249287931. The reversal of 1249287921 is 1297829421.

It is not a de Polignac number, because 1249287921 - 2¹⁷ = 1249156849 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1249287931) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3304806 + ... + 3305183.

It is an arithmetic number, because the mean of its divisors is an integer number (132199800).

Almost surely, 2^1249287921 is an apocalyptic number.

It is an amenable number.

1249287921 is a deficient number, since it is larger than the sum of its proper divisors (865908879).

1249287921 is an equidigital number, since it uses as much as digits as its factorization.

1249287921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6610005 (or 6609999 counting only the distinct ones).

The product of its digits is 145152, while the sum is 45.

The square root of 1249287921 is about 35345.2673069536. The cubic root of 1249287921 is about 1077.0127558021.

The spelling of 1249287921 in words is "one billion, two hundred forty-nine million, two hundred eighty-seven thousand, nine hundred twenty-one".