621661601 has 4 divisors (see below), whose sum is σ = 678176304. Its totient is φ = 565146900.

The previous prime is 621661597. The next prime is 621661637. The reversal of 621661601 is 106166126.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 621661601 - 2² = 621661597 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (621661681) 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, 28257335 + ... + 28257356.

It is an arithmetic number, because the mean of its divisors is an integer number (169544076).

Almost surely, 2^621661601 is an apocalyptic number.

It is an amenable number.

621661601 is a deficient number, since it is larger than the sum of its proper divisors (56514703).

621661601 is a wasteful number, since it uses less digits than its factorization.

621661601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56514702.

The product of its (nonzero) digits is 2592, while the sum is 29.

The square root of 621661601 is about 24933.1426218197. The cubic root of 621661601 is about 853.4629663323.

The spelling of 621661601 in words is "six hundred twenty-one million, six hundred sixty-one thousand, six hundred one".