1620646651 has 24 divisors (see below), whose sum is σ = 1801287936. Its totient is φ = 1449423360.

The previous prime is 1620646607. The next prime is 1620646661. The reversal of 1620646651 is 1566460261.

It is not a de Polignac number, because 1620646651 - 2¹⁷ = 1620515579 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1620646651.

It is not an unprimeable number, because it can be changed into a prime (1620646661) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4590891 + ... + 4591243.

It is an arithmetic number, because the mean of its divisors is an integer number (75053664).

Almost surely, 2^1620646651 is an apocalyptic number.

1620646651 is a deficient number, since it is larger than the sum of its proper divisors (180641285).

1620646651 is a wasteful number, since it uses less digits than its factorization.

1620646651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 643 (or 600 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 37.

The square root of 1620646651 is about 40257.2558801516. The cubic root of 1620646651 is about 1174.6165402712.

The spelling of 1620646651 in words is "one billion, six hundred twenty million, six hundred forty-six thousand, six hundred fifty-one".