2135721 has 8 divisors (see below), whose sum is σ = 3254464. Its totient is φ = 1220400.

The previous prime is 2135719. The next prime is 2135723. The reversal of 2135721 is 1275312.

It is an interprime number because it is at equal distance from previous prime (2135719) and next prime (2135723).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 2135721 - 2¹ = 2135719 is a prime.

It is a super-2 number, since 2×2135721² = 9122608379682, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21), and also a Moran number because the ratio is a prime number: 101701 = 2135721 / (2 + 1 + 3 + 5 + 7 + 2 + 1).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2135723) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 50830 + ... + 50871.

It is an arithmetic number, because the mean of its divisors is an integer number (406808).

2^2135721 is an apocalyptic number.

2135721 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

2135721 is a deficient number, since it is larger than the sum of its proper divisors (1118743).

2135721 is a wasteful number, since it uses less digits than its factorization.

2135721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 101711.

The product of its digits is 420, while the sum is 21.

The square root of 2135721 is about 1461.4106199149. The cubic root of 2135721 is about 128.7799264333.

The spelling of 2135721 in words is "two million, one hundred thirty-five thousand, seven hundred twenty-one".