1722021 has 16 divisors (see below), whose sum is σ = 2686464. Its totient is φ = 960624.

The previous prime is 1722013. The next prime is 1722029. The reversal of 1722021 is 1202271.

It is an interprime number because it is at equal distance from previous prime (1722013) and next prime (1722029).

It is not a de Polignac number, because 1722021 - 2³ = 1722013 is a prime.

1722021 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1722029) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 51 + ... + 1856.

It is an arithmetic number, because the mean of its divisors is an integer number (167904).

2^1722021 is an apocalyptic number.

It is an amenable number.

1722021 is a deficient number, since it is larger than the sum of its proper divisors (964443).

1722021 is a wasteful number, since it uses less digits than its factorization.

1722021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1960.

The product of its (nonzero) digits is 56, while the sum is 15.

The square root of 1722021 is about 1312.2579776858. The cubic root of 1722021 is about 119.8614372869.

Adding to 1722021 its reverse (1202271), we get a palindrome (2924292).

The spelling of 1722021 in words is "one million, seven hundred twenty-two thousand, twenty-one".