1620731 has 4 divisors (see below), whose sum is σ = 1852272. Its totient is φ = 1389192.

The previous prime is 1620679. The next prime is 1620733. The reversal of 1620731 is 1370261.

It is a happy number.

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

It is not a de Polignac number, because 1620731 - 2⁶ = 1620667 is a prime.

It is a super-2 number, since 2×1620731² = 5253537948722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1620733) 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, 115760 + ... + 115773.

It is an arithmetic number, because the mean of its divisors is an integer number (463068).

2^1620731 is an apocalyptic number.

1620731 is a deficient number, since it is larger than the sum of its proper divisors (231541).

1620731 is an equidigital number, since it uses as much as digits as its factorization.

1620731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 231540.

The product of its (nonzero) digits is 252, while the sum is 20.

The square root of 1620731 is about 1273.0793376691. The cubic root of 1620731 is about 117.4636918148.

Adding to 1620731 its reverse (1370261), we get a palindrome (2990992).

The spelling of 1620731 in words is "one million, six hundred twenty thousand, seven hundred thirty-one".