1220100021 has 48 divisors (see below), whose sum is σ = 2125543680. Its totient is φ = 659324160.

The previous prime is 1220099989. The next prime is 1220100023. The reversal of 1220100021 is 1200010221.

It is not a de Polignac number, because 1220100021 - 2⁵ = 1220099989 is a prime.

It is a super-2 number, since 2×1220100021² = 2977288122488400882, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 1220099976 and 1220100012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1220100023) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 124231 + ... + 133691.

It is an arithmetic number, because the mean of its divisors is an integer number (44282160).

Almost surely, 2^1220100021 is an apocalyptic number.

It is an amenable number.

1220100021 is a deficient number, since it is larger than the sum of its proper divisors (905443659).

1220100021 is a wasteful number, since it uses less digits than its factorization.

1220100021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9586 (or 9583 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 1220100021 is about 34929.9301602508. The cubic root of 1220100021 is about 1068.5589302832.

Adding to 1220100021 its reverse (1200010221), we get a palindrome (2420110242).

The spelling of 1220100021 in words is "one billion, two hundred twenty million, one hundred thousand, twenty-one".