1220021731 has 4 divisors (see below), whose sum is σ = 1234720872. Its totient is φ = 1205322592.

The previous prime is 1220021717. The next prime is 1220021767. The reversal of 1220021731 is 1371200221.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1220021731 - 2²¹ = 1217924579 is a prime.

It is a super-2 number, since 2×1220021731² = 2976906048224472722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1220021699 and 1220021708.

It is not an unprimeable number, because it can be changed into a prime (1223021731) 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, 7349446 + ... + 7349611.

It is an arithmetic number, because the mean of its divisors is an integer number (308680218).

Almost surely, 2^1220021731 is an apocalyptic number.

1220021731 is a deficient number, since it is larger than the sum of its proper divisors (14699141).

1220021731 is an equidigital number, since it uses as much as digits as its factorization.

1220021731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14699140.

The product of its (nonzero) digits is 168, while the sum is 19.

The square root of 1220021731 is about 34928.8094701208. The cubic root of 1220021731 is about 1068.5360744335.

Adding to 1220021731 its reverse (1371200221), we get a palindrome (2591221952).

The spelling of 1220021731 in words is "one billion, two hundred twenty million, twenty-one thousand, seven hundred thirty-one".