1620881651 has 4 divisors (see below), whose sum is σ = 1626609432. Its totient is φ = 1615153872.

The previous prime is 1620881611. The next prime is 1620881653. The reversal of 1620881651 is 1561880261.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1620881651 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1620881653) 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, 2863466 + ... + 2864031.

It is an arithmetic number, because the mean of its divisors is an integer number (406652358).

Almost surely, 2^1620881651 is an apocalyptic number.

1620881651 is a deficient number, since it is larger than the sum of its proper divisors (5727781).

1620881651 is an equidigital number, since it uses as much as digits as its factorization.

1620881651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5727780.

The product of its (nonzero) digits is 23040, while the sum is 38.

The square root of 1620881651 is about 40260.1745028508. The cubic root of 1620881651 is about 1174.6733121665.

The spelling of 1620881651 in words is "one billion, six hundred twenty million, eight hundred eighty-one thousand, six hundred fifty-one".