1621775772 has 18 divisors (see below), whose sum is σ = 4099488848. Its totient is φ = 540591912.

The previous prime is 1621775737. The next prime is 1621775777. The reversal of 1621775772 is 2775771261.

1621775772 is a `hidden beast` number, since 1 + 6 + 2 + 1 + 77 + 577 + 2 = 666.

It is a tau number, because it is divible by the number of its divisors (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1621775777) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 22524628 + ... + 22524699.

Almost surely, 2^1621775772 is an apocalyptic number.

1621775772 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

1621775772 is an abundant number, since it is smaller than the sum of its proper divisors (2477713076).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1621775772 is a wasteful number, since it uses less digits than its factorization.

1621775772 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45049337 (or 45049332 counting only the distinct ones).

The product of its digits is 288120, while the sum is 45.

The square root of 1621775772 is about 40271.2772581154. The cubic root of 1621775772 is about 1174.8892660396.

The spelling of 1621775772 in words is "one billion, six hundred twenty-one million, seven hundred seventy-five thousand, seven hundred seventy-two".