1263612721 has 12 divisors (see below), whose sum is σ = 1454748672. Its totient is φ = 1075189464.

The previous prime is 1263612683. The next prime is 1263612739. The reversal of 1263612721 is 1272163621.

It is not a de Polignac number, because 1263612721 - 2¹⁵ = 1263579953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1263612761) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 130576 + ... + 139918.

It is an arithmetic number, because the mean of its divisors is an integer number (121229056).

Almost surely, 2^1263612721 is an apocalyptic number.

It is an amenable number.

1263612721 is a deficient number, since it is larger than the sum of its proper divisors (191135951).

1263612721 is an frugal number, since it uses more digits than its factorization.

1263612721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9628 (or 9489 counting only the distinct ones).

The product of its digits is 6048, while the sum is 31.

The square root of 1263612721 is about 35547.3307155404. The cubic root of 1263612721 is about 1081.1135978779.

The spelling of 1263612721 in words is "one billion, two hundred sixty-three million, six hundred twelve thousand, seven hundred twenty-one".