1247212921 has 4 divisors (see below), whose sum is σ = 1250175844. Its totient is φ = 1244250000.

The previous prime is 1247212913. The next prime is 1247212931. The reversal of 1247212921 is 1292127421.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1292127421 = 13 ⋅99394417.

It can be written as a sum of positive squares in 2 ways, for example, as 26409321 + 1220803600 = 5139^2 + 34940^2 .

It is a cyclic number.

It is not a de Polignac number, because 1247212921 - 2³ = 1247212913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1247212931) 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, 1480830 + ... + 1481671.

It is an arithmetic number, because the mean of its divisors is an integer number (312543961).

Almost surely, 2^1247212921 is an apocalyptic number.

It is an amenable number.

1247212921 is a deficient number, since it is larger than the sum of its proper divisors (2962923).

1247212921 is an equidigital number, since it uses as much as digits as its factorization.

1247212921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2962922.

The product of its digits is 4032, while the sum is 31.

The square root of 1247212921 is about 35315.9018149049. The cubic root of 1247212921 is about 1076.4161386229.

The spelling of 1247212921 in words is "one billion, two hundred forty-seven million, two hundred twelve thousand, nine hundred twenty-one".