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19900000661 = 28393700877
BaseRepresentation
bin10010100010001000…
…011110100110010101
31220100212100202221112
4102202020132212111
5311223400010121
613050354024405
71303066133432
oct224210364625
956325322845
1019900000661
118492039042
123a34578105
131b51a64528
14d6acd4b89
157b70b675b
hex4a221e995

19900000661 has 4 divisors (see below), whose sum is σ = 19900729932. Its totient is φ = 19899271392.

The previous prime is 19900000619. The next prime is 19900000667. The reversal of 19900000661 is 16600000991.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 14633740900 + 5266259761 = 120970^2 + 72569^2 .

It is a cyclic number.

It is not a de Polignac number, because 19900000661 - 214 = 19899984277 is a prime.

19900000661 is a strobogrammatic number because it is the same when read upside-down.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19900000667) 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, 322046 + ... + 378831.

It is an arithmetic number, because the mean of its divisors is an integer number (4975182483).

Almost surely, 219900000661 is an apocalyptic number.

It is an amenable number.

19900000661 is a deficient number, since it is larger than the sum of its proper divisors (729271).

19900000661 is an equidigital number, since it uses as much as digits as its factorization.

19900000661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 729270.

The product of its (nonzero) digits is 2916, while the sum is 32.

The spelling of 19900000661 in words is "nineteen billion, nine hundred million, six hundred sixty-one", and thus it is an aban number.

Divisors: 1 28393 700877 19900000661