1221690 has 32 divisors (see below), whose sum is σ = 2961216. Its totient is φ = 322560.

The previous prime is 1221667. The next prime is 1221707. The reversal of 1221690 is 961221.

It is a super-2 number, since 2×1221690² = 2985052912200, which contains 22 as substring.

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, 5685 + ... + 5895.

It is an arithmetic number, because the mean of its divisors is an integer number (92538).

2^1221690 is an apocalyptic number.

1221690 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1221690 is an abundant number, since it is smaller than the sum of its proper divisors (1739526).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1221690 is a wasteful number, since it uses less digits than its factorization.

1221690 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 414.

The product of its (nonzero) digits is 216, while the sum is 21.

The square root of 1221690 is about 1105.3008640185. The cubic root of 1221690 is about 106.9022894644.

The spelling of 1221690 in words is "one million, two hundred twenty-one thousand, six hundred ninety".