1221712805 has 16 divisors (see below), whose sum is σ = 1534099824. Its totient is φ = 933004800.

The previous prime is 1221712799. The next prime is 1221712813. The reversal of 1221712805 is 5082171221.

It can be written as a sum of positive squares in 8 ways, for example, as 62378404 + 1159334401 = 7898^2 + 34049^2 .

It is not a de Polignac number, because 1221712805 - 2⁶ = 1221712741 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 52496 + ... + 72105.

It is an arithmetic number, because the mean of its divisors is an integer number (95881239).

Almost surely, 2^1221712805 is an apocalyptic number.

It is an amenable number.

1221712805 is a deficient number, since it is larger than the sum of its proper divisors (312387019).

1221712805 is a wasteful number, since it uses less digits than its factorization.

1221712805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 124696.

The product of its (nonzero) digits is 2240, while the sum is 29.

The square root of 1221712805 is about 34953.0085257335. The cubic root of 1221712805 is about 1069.0295463357.

The spelling of 1221712805 in words is "one billion, two hundred twenty-one million, seven hundred twelve thousand, eight hundred five".