1681624551 has 4 divisors (see below), whose sum is σ = 2242166072. Its totient is φ = 1121083032.

The previous prime is 1681624541. The next prime is 1681624559. The reversal of 1681624551 is 1554261861.

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

It is not a de Polignac number, because 1681624551 - 2¹⁵ = 1681591783 is a prime.

It is a super-2 number, since 2×1681624551² = 5655722261051903202, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1681624559) 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, 280270756 + ... + 280270761.

It is an arithmetic number, because the mean of its divisors is an integer number (560541518).

Almost surely, 2^1681624551 is an apocalyptic number.

1681624551 is a deficient number, since it is larger than the sum of its proper divisors (560541521).

1681624551 is an equidigital number, since it uses as much as digits as its factorization.

1681624551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 560541520.

The product of its digits is 57600, while the sum is 39.

The square root of 1681624551 is about 41007.6157682936. The cubic root of 1681624551 is about 1189.1674498195.

The spelling of 1681624551 in words is "one billion, six hundred eighty-one million, six hundred twenty-four thousand, five hundred fifty-one".